Eight of the 12 boys trapped in a flooded and labyrinth cave system in far northern Thailand are safe and recuperating in a hospital after another four were brought out by divers on the second day of a high-stakes rescue operation, a top official said.
They were taken to Chiangrai Prachanukroh Hospital where their four teammates rescued on Sunday had been tested and waiting for an all-clear.
Thai Royal Navy inside the Tham Luang cave on July 7.
Chiang Rai acting Gov. Narongsak Osottanakorn said Saturday that mild weather and falling water levels in recent days had created the "perfect" conditions for an underwater evacuation.
The boys became trapped in the cave on 23 June after heavy rains caused flooding, but were found alive last week by divers.
The boys are said to be generally in good health but doctors are still evaluating whether they could have picked up any risky infections, such as the potentially lethal leptospirosis, while inside the damp cave for two weeks.
"We're going to keep people on site until they get everyone out, the boys, the coach and the divers", Decker said. "And we will do it faster because we are afraid of the rain".
When it was realised that the boys were in the cave system, divers began the process of trying to find them in the enormous area.
Divers took about four hours to escort Monday's fortunate four from the ledge to the chamber, the source added.
Two days before the first four boys were rescued, officials warned that oxygen levels with in the cave had fallen to 15%.
In all, 12 boys and their coach had been stuck in the Tham Luang cave network since June 23, when water levels partially flooded the escape routes.
Monday's mission began with eight boys and their 25-year-old coach still underground, all of whom have spent more than two weeks in the cave in Chiang Rai province.
Onlookers watch and cheer during the rescue operation.
The operation to rescue the boys, ages 11-16, and their 25-year-old coach by having them dive out of the flooded cave began Sunday morning, with expert divers entering the sprawling complex for the complicated and risky mission.
Authorities have not confirmed the identity of the first four boys rescued. The families have not yet been able to interact with the boys out of fears of infection.
Relatives said the boys had been inside the labyrinthine complex during the dry season.
The only way to bring the boys and their coach out of the cave is by navigating dark and tight passageways filled with muddy water and strong currents, as well as oxygen-depleted air.
Narongsak said that the "same multinational team" that went into the cave on Sunday to retrieve the first four boys was deployed on Monday. He addressed the rescue mission on Monday at the unveiling of a new project in Bangkok, where reporters asked him how many days it would take to get the boys out.
The four rescued boys have been transported to a Chiang Rai hospital for treatment and medical evaluations, reported CBS.
Divers involved in the rescue described treacherous conditions, with fast-moving shallow water passing through very narrow passages. "We can't visit our boys in hospital because they need to be monitored for 48 hours", Somboon told Reuters.
Narongsak defended the lack of public disclosure of the names of the boys who had already been guided to safety, saying it "will create ill feeling" if their names are released while others languish inside the cave.