Of the 13-strong foreign dive team - mainly from Europe - three escorted the children, while the remainder were positioned along the unsafe first kilometre stretch, where the boys had to navigate through submerged passageways in some places no more than two feet (0.6 metre) wide. Reuters news agency reported that six boys have been rescued, citing a senior member of the medical team involved in the rescue. An entire floor of the 14-story hospital has been reserved for treating the soccer team, according to local media reports.
There will be two divers per child during the rescue operation, and the 12 kids and their coach will come out one-by-one.
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. But they remain "at war with water and time" as torrential monsoon downpours deluged the Tham Luang cave, in the hilly jungle of northern Thailand, and threatened to flood it even further.
But Narongsak said earlier that recent mild weather and falling water levels had created optimal conditions for an underwater evacuation. A Thai Navy SEAL commander told reporters he believed there was "a limited amount of time" left to rescue the team, who wandered into the caves on June 23 after soccer practice.
The boys and the coach will dive out of the cave one at a time, each accompanied by a member of a team of global and Thai divers, officials said.
The 25-year-old soccer coach has written as well, thanking people for support and apologizing to the parents of the boys.
Sustained heavy rains could make the water rise to the shelf where the children were sitting, reducing the area to "less than 10 square meters", he added. He has also thanked global experts who helped find the boys. Each of the boys will be accompanied by two divers.
A Thai military helicopter, allegedly carrying some of the boys among a group of 13 trapped inside a flooded Thai cave, lands at a field in the Mae Sai district of Chiang Rai province on July 8, 2018.
In the hours preceding the rescue, a letter the boys had sent to their families was published on the Thai SEALs' Facebook page.
To escape, the boys must dive through dark, narrow passageways sometimes no more than two feet (0.6 metre) wide, that have challenged some of the world's leading cave divers.
The rescue operation claimed the life of a former Thai navy diver last week.
Last night, the Thai king led tributes to rescuers and the schoolboys as scenes of joyful weeping nationwide were shown on television.
"Today is the D-Day for the rescuers", said Narongsak Osottanakorn, the outgoing governor of Chiang Rai province. One boy's note said: "I'm doing fine, but the air is a little cold, but don't worry".
An Australian doctor checked the health of the boys on Saturday night and gave the all-clear for the operation to proceed.
"I just heard his name, Mongkhol, and I was happy enough", she told the Guardian.