Austin, Texas (CNN) Austin police just confirmed what residents have feared for weeks -- a suspected serial bomber is on the loose.
For the fourth time this month, a device exploded on Austin residents. What makes Sunday night's blast especially terrifying is that the device was left on the side of a residential road and triggered by a tripwire, police said Monday.
Investigators have found similarities between that device and three previous bombs, which were stuffed inside packages and left on residents' doorsteps, Austin Police Chief Brian Manley said.
"We are clearly dealing with what we expect to be a serial bomber at this point," he said.
The latest device -- which was triggered by a tripwire -- shows "a higher level of sophistication, a higher level of skill," he said.
And unlike the victims of the previous blasts, the two men injured in Sunday's explosion are white, Austin police said. Both men are expected to recover.
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The Travis Country neighborhood of Austin will remain on lockdown until 2 p.m. CT, Manley said, as authorities investigate the pieces of evidence strewn across a wide area.
Manley asked anyone in the neighborhood with security camera footage to call police.
The Austin public school district says it couldn't send buses to the affected neighborhood Monday because of police activity.
"As the bombmaker changes up design and geography, all residents of Austin and surrounding areas should avoid suspicious items," the global think tank Stratfor Threat Lens said.
An indiscriminate wake-up call
Many minority residents in Austin have been on edge since the bombings started, as the first three bombings killed or wounded minorities.
Several residents under lockdown Monday said they were stunned the latest attack happened in their neighborhood.
Unlike the first three bombings, which happened in east Austin, the latest attack happened in a predominately white part of town.
Eliza May said because the first three bombings happening on the east side of the city, in predominately minority areas, she hadn't been following the news closely.
May said as a resident of the affluent Travis Country neighborhood , she assumed she had nothing to worry about.
"We feel safe. This isn't something that you'd expect around here," May told CNN.
Now, "it's obvious that you have to be alert."
"This was a random bomb," she said. "This could have been any one of us."
Neighbor Shonda Mace said the bombing "is going to be life-changing event for our neighborhood."
"I'm scared about what's going to happen next," she said.
Tripwire could give clues
"The use of a tripwire is far less discriminating than leaving parcel bombs at residences and suggests that the latest victims were not specifically targeted," Stratfor Threat Lens said.
"The device's success, despite significantly different design, further suggests that the bombmaker behind these attacks is an accomplished one, and has likely to have received some training, perhaps as a military or police explosive ordnance disposal technician."
'Extra level of vigilance' needed
The latest blast came less than a week after police said the three previous explosions -- in a span of 10 days -- were connected. Those blasts killed a man and a teenager, and injured two others.
Police are working under the belief that the explosions are related. Manley said they'll get a better idea with a post-blast analysis and examination of the device components.
In the meantime, Manley told residents not to touch or go near anything that looks suspicious.
"We now need the community to have an extra level of vigilance and pay attention to any suspicious device -- whether it be a package or a bag, a backpack -- anything that looks out of place," Manley said Monday. "Do not approach items like that."
Shortly before the fourth bombing, the reward for information leading to the arrest of anyone responsible for the three blasts increased to a total of $115,000, authorities said.
Officials have urged residents to call police with any tips they may have, even if the information seems to be "inconsequential."
(CNN) Four bombings in 17 days have left the Texas capital on edge, as Austin police are warning the public not to take chances : If it looks suspicious -- whether it's a package, box or backpack -- do not approach it.
While authorities are offering a six-figure reward for information leading to an arrest in the bombings, which have killed two people , the latest attack Sunday seemed to follow a different pattern.
Where the first three package bombs were left on people's doorsteps or porches and killed or injured minorities, the most recent bomb Sunday was left on the side of the road in a predominantly white neighborhood and may have been triggered by a tripwire.
Still, authorities say "similarities" among the bombs have investigators operating under the belief all the bombs are related They suspect a serial bomber is behind the violence. Here's a look at what police say about each attack:
March 2
Anthony Stephan House was killed in the first of four bombings to rock Austin.
The first blast was reported about 6:55 a.m. local time in the Harris Ridge neighborhood of north Austin. It was a powerful device, essentially a pipe bomb, in a normal-sized delivery box, which would be a theme for the first three bombings.
Anthony Stephan House, 39, died from injuries he suffered after opening the package.
His LinkedIn profile said he was a senior project manager for Texas Quarries and participated in commercial projects throughout the state, including at University of Texas properties and the Phillips 66 headquarters in Houston.
March 12
Draylen Mason was a promising student and bassist in a youth orchestra.
The first of two bombs that day, it was detonated around 6:44 a.m. in the city's East MLK neighborhood. Like the bomb 10 days earlier, it had been left at the victim's home and it appeared to have been hand-delivered, rather than by any courier service. The bomb detonated when the victim brought it inside and opened it.
It killed 17-year-old Draylen Mason, a promising student who played stand-up bass in a youth orchestra and was taking college classes while in high school. A woman injured in the bombing suffered non-life-threatening injuries. Neighbors saw her in the yard covering her face with her hands and brought her blankets because the blast had ripped off some of her clothing, said Anne Marie Castillo, who lives five houses down from Mason.
Mason and House were both African-American.
"(Mason) was a young guy with so much future and potential. We talked a lot about college. He hugged me every morning before class," Austin Community College professor Samuel Osemene said.
March 12 again
JUST WATCHED Deadly package bombs were left on doorsteps Replay More Videos ... MUST WATCH Deadly package bombs were left on doorsteps 01:56
Police were processing the scene at the East MLK bombing when another bomb erupted in the Montopolis neighborhood of southeast Austin, a few miles from Austin-Bergstrom International Airport.
The midday blast left a 75-year-old Hispanic woman badly injured, spurring police to leave open the possibility the bombings are hate crimes, given the victims were, at this point, all minorities.
"We believe that the recent explosive incidents that have occurred in the city of Austin were meant to send a message ," Austin Police Chief Brian Manley said.
March 18
JUST WATCHED Police: Tripwire may have triggered explosion Replay More Videos ... MUST WATCH Police: Tripwire may have triggered explosion 01:42
This was the first explosion to break with the pattern of doorstep deliveries. Instead, this bomb was left on the side of the road in the upscale Travis Country neighborhood of southwest Austin. It could have maimed any passerby , police said.
Two white men, a 22- and 23-year-old, who were walking alongside the road when the bomb detonated, were taken to a hospital with serious but non-life threatening injuries.
Despite the new modus operandi, Manley said investigators believe the bombings are connected. Hundreds of federal agents are now involved in the investigation.
Four bombings this month in Austin, Tex., including one on Sunday night, have killed two people and injured four, and put the state capital on high alert.
Date Description March 18 Package on the side of the road injured two March 12 Package outside house injured a 75-year-old woman March 12 Package outside house killed one and injured another March 2 Package on front porch killed one
4 Bombing on Sunday Night
The authorities responded to Dawn Song Drive in southwest Austin after reports of an explosion around 8:30 p.m. on Sunday. Two men in their 20s were seriously injured, according to the Austin-Travis County Emergency Medical Service.
In a press briefing, Chief Brian Manley of the Austin Police Department reported that a package was left on the side of the road and that the bomb was possibly triggered by tripwire, unlike the previous bombings.
The scene outside the bombing on Sunday night that injured two people. Nick Wagner/Austin American-Statesman, via Associated Press
2 3 Two Bombings on March 12
An explosion was reported on Oldfort Hill Drive in East Austin at about 6:45 a.m. on March 12; a 17-year-old, Draylen Mason, was killed and his mother was critically injured. She opened a package in the kitchen after bringing it in from the front porch of her house, according to Chief Manley.
Later that morning, at about 11:50 a.m., another explosion was reported on Galindo Street, only a few miles away. A 75-year-old Hispanic woman was significantly injured when she picked up a package left outside of her house.
The scene near Galindo Street after the bombing. Suzanne Cordeiro/Agence France-Presse -- Getty Images
1 First Bombing on March 2
At about 6:55 a.m. on March 2, Anthony Stephan House, 39, was killed after he handled a box left on his front porch.
Outside the residence of Anthony Stephan House. Tamir Kalifa for The New York Times
The damage at the doorway of the house, partly covered by plywood. Jon Herskovitz/Reuters
The Common Links
In a press briefing after the second round of bombings, the Austin Police Department confirmed that the three cases on March 2 and March 12 were linked.
“What we have right now are similarities that we believe link the three cases together,” Chief Manley said.
All three incidents involved cardboard packages that were left on doorsteps overnight, according to the police chief. None of the packages were delivered through the Postal Service or any other delivery services.
The police have so far been unable to identify any motives or commonalities between the victims.
The #FBI, ATF, and Austin Police Department seek the public's assistance with identifying the individual(s) responsible for the package bombs which injured and killed several Austin, Texas, residents. Reward offered: https://t.co/fcGIut3Ou8 pic.twitter.com/wjdbWZciQZ — FBI Most Wanted (@FBIMostWanted) 2018年3月18日
“We are not ruling anything out at this point,” Chief Manley said when asked about the potential targets of the attacks. “Because when you rule something out, you limit your focus of the investigation and you might miss something.”
Two of the people killed after handling the packages were members of African-American families with deep roots in the city’s black, religious and civil-rights groups.
Moments later, dozens of police cars, ambulances and fire trucks swarmed her street, Ms. May said. Police officers ordered neighbors — who had come outside to see what happened — to return to their homes, she said.
Investigators from the F.B.I. and the Bureau of Alcohol, Tobacco, Firearms and Explosives also responded to the neighborhood known as Travis Country, which is about five miles southwest of downtown Austin and in a different area from the three previous explosions. Bomb technicians with the A.T.F. were conducting a secondary sweep, officials said.
Because the device exploded after nightfall, the chief said, the police could not fully inspect the scene and would have to wait until sunrise on Monday to better examine it. It was not immediately clear if Sunday’s explosion was directly connected to the three previous bombings.
“We have not had an opportunity to really look at this blast site to determine what has happened,” Chief Manley said at an evening news conference. “It’s obvious that there’s been an explosion, and it’s obvious it’s caused significant injuries to two people.”
At a news conference before Sunday’s explosion, the Austin police made a rare public appeal for the bomber or bombers responsible for the first three explosions to contact the police so officials could learn more about the “message” behind the attacks.
“These events in Austin have garnered worldwide attention, and we assure you that we are listening,” Chief Manley said in addressing the unknown bomber or bombers at the earlier news conference. “We want to understand what brought you to this point, and we want to listen to you.”
Chief Manley told reporters that he hoped the person or people responsible were watching, and that they would get in touch by calling 911 or reaching out online. He said investigators had not established a motive for the explosive packages.
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“There’s the message behind what’s happening in our community, and we’re not going to understand that until the suspect or suspects reaches out to us to talk to us about what that message was,” Chief Manley said. “We still do not know what ideology may be behind this and what the motive was behind this.”
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Before Sunday, three separate bombings this month in the eastern and northeastern parts of the city left two people dead and a third seriously wounded. In each case, the victims handled packages that were left on their doorsteps and were outfitted with homemade but sophisticated explosive devices.
Officials said the first bombing, on Haverford Drive on March 2, and two more on March 12, on Oldfort Hill Drive and Galindo Street, were connected. None of the packages were mailed. Instead, they were apparently placed directly near the doors of homes for the victims to find. In two cases, the bombs detonated when the victims picked them up; in the third, the package exploded after it had been carried inside and opened.
More than 500 federal agents are assisting the investigation from agencies including the F.B.I. and the A.T.F. Fred Milanowski, the A.T.F. special agent in charge of its Houston division, said he believed that the same person built all three devices.
“Every bomber that makes these leaves a signature,” Mr. Milanowski said. “Obviously, once they find something successful for them, they don’t want to deviate from that because they don’t want something to blow up on them.”
Mr. Milanowski said a degree of skill was required to assemble, transport and deliver the devices without an accidental explosion. He declined to identify the materials that were used to make them.
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“It wouldn’t be a typical household that would have all these components, but I would say that all the components are commercially available,” he said.
Since March 12, the day when two bombings occurred, anxious residents have reported hundreds of suspicious packages to the authorities; Austin police officers have responded to 735 such calls. Officials have continued to urge residents to call 911 if they receive a package that they were not expecting and that did not appear to have been delivered by the Postal Service or a legitimate commercial service like U.P.S. or FedEx.
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Law enforcement officials said they were looking for possible links to similar residential package bombings across the country.
“The scope goes beyond just Austin,” said a law enforcement official who spoke on condition of anonymity to discuss a continuing investigation. “We’re looking for anyone that could have been involved in making bombs in the past in Texas, and really anywhere in the United States.”
Asked at the news conference whether investigators were looking for links to bombings elsewhere, Chief Manley said they were pursuing all avenues. “We are not going to rule anything out until we have a reason to rule it out,” he said, “because when we do that, it narrows our focus and we may limit considering things that we should be considering.”
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Over the past 30 years or so, package bombings have killed or wounded more than two dozen people across the country, excluding those connected to the Unabomber case. Many of the attacks have been solved by the authorities; they often stemmed from domestic disputes, and sometimes involved pipe bombs in packages wrapped like holiday presents.
The bombings in Austin have alarmed black leaders because the two people killed were African-American and the seriously wounded victim was a 75-year-old Hispanic woman. Law enforcement officials said that they did not have conclusive evidence that race played a role in the bombings, but that they were continuing to explore the possibility.
Nelson E. Linder, the president of the Austin branch of the N.A.A.C.P., said on Sunday evening that he did not know the race of the two men injured in the latest explosion. “It’s important for the whole city to understand this is a danger, and I think tonight kind of confirms that,” Mr. Linder said. “I think that’s what this means tonight, that this whole city is at risk.”
Investigators are examining connections between the two black victims, who both belonged to prominent African-American families. Officials said investigators were also looking into the possibility that the bomb that wounded the Hispanic woman may have been intended for someone else, but that nothing definitive had been established.
Chief Manley said on Sunday that the combined rewards offered for information leading to an arrest and conviction in the case had been increased to $115,000, from $65,000.
A concert featuring the Roots that was part of the South by Southwest festival in Austin was canceled on Saturday after the concert venue received a bomb threat in an email, the authorities said. No device was found, and the police later arrested a man on a charge of making a terroristic threat. The police said the man, Trevor Weldon Ingram, 26, was not a suspect in the package bombings.