The rescued boys emerged as night fell from the Tham Luang cave complex after divers guided them along a route of more than four kilometres (2.5 miles) that included twisting, extremely narrow and jagged passageways filled with water.
Their escape led to an explosion of jubilation on social media in Thailand as the rescued boys were rushed to hospital.
But the survival of those remaining in the cave is far from guaranteed with extraction efforts put on hold until Monday morning to allow rescue divers time to resupply.
Rescue chief Narongsak Osottanakorn said the four who escaped were “safe” but released few details about their condition or identities.
Footage released by authorities showed groups of soldiers carrying what appeared to be two of the boys on stretchers into the back of waiting ambulances which then sped off for a nearby hospital.
The group became trapped in a cramped chamber deep inside Tham Luang in a mountainous area of northern Thailand on June 23, when they went in after football practice and got caught behind rising waters after a torrential downpour.
Their plight transfixed Thailand and the rest of the world, as authorities struggled to locate them and then devise a plan to get the boys — aged between 11 and 16 — and their 25-year-old coach out.
The group was found dishevelled and hungry by British cave diving specialists nine days after they ventured in.
Initial euphoria over finding the boys alive quickly turned into deep anxiety as rescuers struggled to find a way to get them out.
The death of a former Thai Navy SEAL diver who ran out of oxygen in the cave on Friday underscored the danger of the journey even for professionals.
– ‘D-Day’ –
Foreign elite divers and Thai Navy SEALS were forced to begin the complex operation to extract the boys earlier than they had hoped on Sunday morning because forecast rainfall was threatening more flooding that might doom the mission.
“Today is the D-day. The boys are ready to face any challenges,” Narongsak told reporters near the cave site on Sunday morning.
The rescue of the initial batch of boys was a stunning victory in an operation Narongsak had earlier dubbed “Mission Impossible” and led to cautious optimism that the others would also be saved.
Narongsak described the extraction of the initial group of four as “smooth”.
But efforts to get the others out were put on hold until Monday morning to give rescue workers time to replenish stocks of oxygen and other supplies.
“We need to refill,” Narongsak said.
Experts say a rescue mission through a flooded cave is dangerous enough for professionals, let alone young boys who have never dived before.
“It is an extremely risky undertaking,” Bill Whitehouse, vice chairman of the British Cave Rescue Council, told AFP, adding “poor visibility in the water, tortuous passages to get through, constrictions” were some of the major obstacles divers face.
– Treacherous journey –
Narongsak said two divers would escort each of the boys out of the cave. Ropes have also been installed to help guide the boys through the darkness.
Authorities had looked at many different ways to save the boys and their coach.
One early potential plan was to leave them there for months until the monsoon season ended and the floods subsided completely, but that idea was scrapped over concerns about falling oxygen levels and waters rising too high.
More than 100 exploratory holes were also bored into the mountainside in an attempt to open a second evacuation route and avoid forcing the boys into the dangerous dive.
American technology entrepreneur Elon Musk even deployed engineers from his private space exploration firm SpaceX and Boring Co. to help.
Meanwhile rescuers fed a kilometres-long air pipe into the cave to restore oxygen levels in the chamber where the team was sheltering with medics and divers.
Thais were quick to jump onto social media on Sunday night to celebrate the rescue of the initial four.
“The rescue team of the Wild Boars should be given this year’s World Cup trophy,” one person wrote on Facebook, referring to the boys by the name of their football team. DM