Tham Luang caves, Thailand (CNN) Four of the 12 boys who have been trapped in a flooded cave in northern Thailand for more than two weeks have been rescued, as the operation was put on hold overnight to allow oxygen tanks to be refilled.
The mission to free the remaining members of the group has been suspended for at least 10 hours, Chiang Rai Governor Narongsak Osotthanakorn said, as teams replenish supplies used up removing the first four boys.
But authorities face a new race against time as heavy rain, which had been predicted later this week, pummeled the cave complex in northern Thailand shortly after the first boys were freed.
The boys, who are due to be taken to Chiang Rai hospital for further medical examination, are said to be in good health, with their condition described by officials as "not that bad."
An ambulance leaves the Tham Luang cave area after divers evacuated some of the 12 boys trapped with their coach for 15 days.
Confirmation of the initial rescue was posted on the Thai Navy SEAL official Facebook page late Sunday evening, several hours ahead of the initial schedule provided by authorities.
The first of the four boys emerged from the cave entrance about nine hours after a team of 18 international cave diving experts entered the underground chamber to begin the hazardous process of accompanying the boys through the flooded, narrow tunnels to safety.
Previously, the entire round trip through the cave network was thought to take roughly 11 hours to complete, but efforts to drain the tunnels of flood water appear to have shortened the journey time by at least three and a half hours.
A helicopter lands at a military airport in Chiang Rai on Sunday, with its passengers taken by ambulance to a nearby hospital.
Two ambulances leave the military airport in Chiang Rai, headed to a nearby hospital after the rescue operation.
The boys wore "full face masks and the rescue divers carried them out through the passage in the cave complex," Governor Osotthanakorn told a news conference after the rescue. "It was a very smooth operation today," he added.
Sunday's mission actually went quicker than it had in rehearsals, Osotthanakorn said, which took place over the last three to four days.
While the governor would not confirm the identities of the four boys, he said the first one emerged at 5:40pm local time, followed by the second boy 10 minutes later. Two other boys emerged from the cave at 7:40pm and 7:50pm local time.
Families of the children have been waiting anxiously for news following authorities' decision to initiate the rescue attempt at 10 a.m. local time Sunday, as storm clouds threatened to dump more water on the flooded caverns, undoing efforts to drain them.
Twelve boys -- aged between 11 and 16 -- and their coach, were discovered by two British divers on July 2, nine days after they disappeared during an outing in the Tham Luang Nang Non cave complex, in Chiang Rai, northern Thailand.
Those still inside the cave are perched on a small muddy ledge four kilometers (2.5 miles) inside the cave complex, surrounded by flood water and with a limited supply of oxygen.
Race against time
For the boys, the most dangerous part of the journey out of the labyrinth cave system remains the first kilometer, in which they are required to pass through a flooded channel no wider than a person. During this process, rescuers need to hold their oxygen tanks in front of them and swim pencil-like through submerged holes.
Having completed this section, the boys are then handed over to separate, specialist rescue teams, who help assist them through the remainder of the caves, much of which they can wade through.
But rescuers have a dwindling window of opportunity, with forecasters predicting the return of heavy monsoon rains in the coming days, effectively sealing off the cave until October.
"We have two obstacles: water and time. This what we have been racing against since day one. We have to do all we can, even though it is hard to fight the force of nature," Osotthanakorn said earlier, as rain began to fall across the site.
The prospect of a downpour has been looming over rescuers since the very beginning. It was the rain that stranded the boys and their coach inside the caves to begin with, after they left their bicycles and ventured into the cave network late last month.
"The heaviest rain has yet to come," said CNN meteorologist Allison Chinchar.
Rescue teams have been helped by the fact that the rain stopped for several days, Chinchar said, allowing water to be pumped out of the caves and making it possible for the four boys and specialist rescue teams to make the final leg of the journey on foot.
But that could change in the coming days, Chinchar added. Monday, Tuesday and Wednesday each have an 80% to 90% chance of rain.
"And really when you look at the long-term forecast, it really extends the next 7 to 10 days," she said.
Osotthanakorn told reporters there would be a meeting Sunday evening to plan next steps, and that authorities want to ensure conditions are stable before beginning the next phase of the rescue.
A rescue mission like no other
Divers have previously described conditions in the cave network as some of the most extreme they have ever faced.
The decision to move the boys using divers has not been taken lightly. On Friday, a former Thai Navy SEAL died while returning from an operation to deliver oxygen tanks to the cave where the boys are located.
Photos: Thai soccer team trapped in cave Ambulances wait on standby outside a hospital in Chiang Rai province on Sunday, July 8, where the rescued boys will be treated. The first four members of the team have been evacuated. Hide Caption 1 of 38 Photos: Thai soccer team trapped in cave Thai rescue teams arrange a water pumping system at the entrance to a flooded cave complex where 12 boys and their soccer coach became trapped June 23 in Mae Sai, Chiang Rai province, northern Thailand, on Saturday, July 7. Hide Caption 2 of 38 Photos: Thai soccer team trapped in cave Emergency responders surround a helicopter prior to departing for the hospital on Sunday, July 8, after members of the soccer team had been rescued. Hide Caption 3 of 38 Photos: Thai soccer team trapped in cave Thai military personnel walk up into a cave during the ongoing rescue operations Saturday. Hide Caption 4 of 38 Photos: Thai soccer team trapped in cave An ambulance heads from Tham Luang Nang Non cave toward a hospital on July 8, 2018, in Chiang Rai, Thailand after reports that a rescue mission was underway for 12 boys and their soccer coach who were trapped in the flooded cave system. Hide Caption 5 of 38 Photos: Thai soccer team trapped in cave Thai military personnel work inside a cave during the ongoing rescue operations. Hide Caption 6 of 38 Photos: Thai soccer team trapped in cave An ambulance leaves the scene of the rescue effort at the Tham Luang Nang Non cave system on Sunday, July 8. Hide Caption 7 of 38 Photos: Thai soccer team trapped in cave An ambulance leaves the Tham Luang Nang Non cave area after reports that some of the boys had been rescued. Hide Caption 8 of 38 Photos: Thai soccer team trapped in cave Rescuers lock hands prior to leaving for a rescue operation. Hide Caption 9 of 38 Photos: Thai soccer team trapped in cave Family members pray in front of a Buddhist statue near the cave Saturday. Hide Caption 10 of 38 Photos: Thai soccer team trapped in cave Emergency workers carry oxygen tanks as rescue operations are underway. Hide Caption 11 of 38 Photos: Thai soccer team trapped in cave Thai soldiers work to connect pipes that will help water from entering a cave. Hide Caption 12 of 38 Photos: Thai soccer team trapped in cave Thai forest rangers examine a map as they review their options during the ongoing rescue operations Saturday. Hide Caption 13 of 38 Photos: Thai soccer team trapped in cave This image, taken from video on Monday, July 2, shows the youth soccer team that has been trapped in a Thai cave since June 23. Hide Caption 14 of 38 Photos: Thai soccer team trapped in cave Divers have been able to bring food, blankets and other supplies to the boys while experts debate how to get them out safely. The team was found around two kilometers (1.24 miles) into the cave and somewhere between 800 meters to one kilometer below the surface, according to a British Cave Rescue Council briefing note. Hide Caption 15 of 38 Photos: Thai soccer team trapped in cave The team was found alive by British divers. The search has brought rescue teams from all over the world. Hide Caption 16 of 38 Photos: Thai soccer team trapped in cave A Thai military medic provides first aid to one of the boys. Hide Caption 17 of 38 Photos: Thai soccer team trapped in cave The body of Saman Kunan, a former Thai Navy SEAL, is carried during a repatriation and religious rites ceremony on Friday, July 6. Kunan died at 2 a.m. Friday as he returned from an operation to deliver oxygen tanks to the cave. He ran out of air while underwater, an official said. Hide Caption 18 of 38 Photos: Thai soccer team trapped in cave Thai police take a break for breakfast as rescue operations continue on Wednesday, July 4. Hide Caption 19 of 38 Photos: Thai soccer team trapped in cave Water is pumped out of the cave during rescue efforts on Tuesday, July 3. Hide Caption 20 of 38 Photos: Thai soccer team trapped in cave Workers fix the road leading to the cave on July 3. Hide Caption 21 of 38 Photos: Thai soccer team trapped in cave Divers prepare a light to be used for the underwater search on Monday, July 2. Hide Caption 22 of 38 Photos: Thai soccer team trapped in cave Rescue workers wait at the entrance to the cave on July 2. Hide Caption 23 of 38 Photos: Thai soccer team trapped in cave Some of the team's family members celebrate after receiving news that the team was alive. Hide Caption 24 of 38 Photos: Thai soccer team trapped in cave Technicians lift water pumps to the drilling site on Sunday, July 1. Hide Caption 25 of 38 Photos: Thai soccer team trapped in cave Soldiers and rescuers work outside the cave complex on July 1. Hide Caption 26 of 38 Photos: Thai soccer team trapped in cave Monks attend a Buddhist prayer for the team on July 1. Hide Caption 27 of 38 Photos: Thai soccer team trapped in cave Scuba tanks are delivered to the search site on July 1. Hide Caption 28 of 38 Photos: Thai soccer team trapped in cave Rescue workers carry water-pumping equipment into the cave on July 1. Hide Caption 29 of 38 Photos: Thai soccer team trapped in cave A Thai Air Force worker drops near a possible cave opening on Saturday, June 30. Hide Caption 30 of 38 Photos: Thai soccer team trapped in cave British cave diver Robert Charles Harper explores an opening on Friday, June 29. Hide Caption 31 of 38 Photos: Thai soccer team trapped in cave Relatives of the trapped team members pray on Wednesday, June 27. Hide Caption 32 of 38 Photos: Thai soccer team trapped in cave Family members waited more than a week for news of their loved ones. Hide Caption 33 of 38 Photos: Thai soccer team trapped in cave Thai soldiers bring hoses and additional water pumps as the search for the team continued on June 27. Hide Caption 34 of 38 Photos: Thai soccer team trapped in cave Volunteer paramedics wait near the cave entrance on June 27. Hide Caption 35 of 38 Photos: Thai soccer team trapped in cave A rescuer looks for a cave entrance on June 27. Hide Caption 36 of 38 Photos: Thai soccer team trapped in cave Rescuers search the cave on Tuesday, June 26. Hide Caption 37 of 38 Photos: Thai soccer team trapped in cave Thai soldiers relay cable at the search site on June 26. Hide Caption 38 of 38
Finnish volunteer diver Mikko Paasi, a long-term resident of Thailand, said the death of the Thai Navy SEAL had changed the mood on the ground and made real for rescuers just how dangerous the mission had become.
"Definitely, you can feel it that it has an effect, but we're moving on. Everyone is a professional so we're trying to put it away and avoid it happening again," he said, adding: "Everybody is focusing on getting these boys out -- keeping them alive or getting them out."
Parents' constant vigil
In the hours preceding the rescue, a letter the boys had sent to their families was published on the Thai SEALs' Facebook page. The letter shows the boys in good spirits despite their ordeal.
JUST WATCHED CNN talks to father waiting for trapped son Replay More Videos ... MUST WATCH CNN talks to father waiting for trapped son 02:37
In neat blue handwriting, 11-year-old Chanin Viboonrungruang, the youngest of the group, told his parents not to worry, and said he was looking forward to eating fried chicken.
His parents, who along with other families, have maintained a constant vigil at the site since the boys first became trapped.
On reading the letter Saturday evening, Chanin's father, Tanawut Viboonrungruang, said he felt a great sense of relief. "I had been worried about my son, that he would be exhausted, he would be tired," he said.
Now, more than two weeks after their children became trapped in a flooded cave, some of the families are finally celebrating their return.
Rescued boys begin the recovery process
Now that the first of the boys have been taken to a nearby hospital, doctors there will begin evaluating the impact to their long-term health
One of the primary concerns will be the boys' exposure to a lack of oxygen, said Dr. Darria Long Gillespie of the University of Tennessee. "As soon as they get out, that's what they'll be checking: their oxygen levels and their breathing."
Thai officials said Friday that oxygen levels inside the cave plummeted to a dangerous 15% -- shy of the US Department of Labor's Occupational Safety and Health Administration's " optimal range " of oxygen, which is between 19.5% and 23.5%.
As oxygen drops below the lower threshold of the optimal level, the body begins to undergo changes and may face the serious risk of hypoxia, the condition that causes altitude sickness, according to OSHA.
The boys will also be checked for malnutrition, dehydration and an array of other health effects.
As the first members of the boys' soccer team trapped in a cave in Thailand were rescued Sunday, the focus begins to shift to the boys' long-term health and getting them proper medical aid.
Oxygen is a top priority. Health experts said, authorities would first be checking the rescued boys' exposure to a lack of oxygen while in the cave. Thai officials on Friday said oxygen levels in the cave air plummeted dangerously to just 15%.
"One of the major concerns is oxygen right now. They've been in an area where oxygen levels are low," Dr. Darria Long Gillespie of the University of Tennessee School of Medicine told CNN. "As soon as they get out, that's what they'll be checking: their oxygen levels and their breathing."
They will also be checked for malnutrition, dehydration and an array of other health effects.
Dr. Carole Lieberman, a psychiatrist who is also a scuba diver, said it would be extremely important to relay the good news of the first boys' rescue to the others who remain trapped inside. "That would be such a boost for their confidence," she said.
The rescue is two-pronged: to help the boys who have been brought out of the cave, while working to save the remaining boys and coach still trapped inside. The rescue operation, authorities said, has paused for the night. Authorities said oxygen tanks needed to be refilled before continuing.
[UPDATED at 11:20 a.m. Eastern, July 8]
The Times has reporters on the scene and will be providing updates regularly. Go here to see maps and diagrams of how the rescue is unfolding.
• The first four rescued players were at the hospital, military and local officials said. But it will be hours — from 10 to 20, according to the search chief — before other boys can start the trip. Divers will be replacing air tanks and supplies along their route until then.
• In the town where the soccer team is based, the celebration was exuberant, even as families awaited word on the rest of the team.
• The rescues came as heavy monsoon rains returned to the area, after days of relative respite. Experts say the rain will not immediately make water levels rise within the cave, but it greatly increases the urgency of the operation.
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