Authorities have said extracting the entire team from the cave could take up to four days, but Sunday's success raised hopes that it could be done faster.
Authorities have said the boys are being held close to divers and wear oxygen masks to enable normal breathing.
Thirteen foreign divers and five members of Thailand's elite navy SEAL unit make up the main team guiding the boys to safety. Authorities have repeatedly said the rain could re-flood crucial parts of the cave complex that have been drained and make the escape route march harder or even impossible to navigate. "I can help him with his homework", he said. "The children complained that they were hungry and wanted holy basil stir-fried rice", Narongsak Osottanakorn, the head of the rescue operation, told reporters on Monday, referring to a popular Thai dish.
Pure Flix Entertainment is seeking the movie rights of the mission that saw the rescue of a dozen boys who were trapped deep within a labyrinth, confirmed Variety.
Earlier, heavy rains in Chiang Rai province threatened to further delay the rescue operations.
Earlier, Narongsak told a news conference a team had gone into the cave to rescue the remaining boys at 11 a.m. (0400 GMT), and he expected good news. The Associated Press reports that four ambulances were seen leaving the area near the cave entrance on Monday, with patients taken to waiting helicopters.
The boys have been brought out in pairs, each guided by two expert divers. Monsoon flooding blocked off their escape and prevented rescuers from finding them for nearly 10 days.
A deluge could overwhelm efforts to lower water levels in the caves - more than 32 million gallons of water were pumped out after the boys were found last Monday.
But with oxygen levels inside dropping to unsafe lows and the prospect of heavy rains flooding the area completely, authorities decided they had to move quickly and take the group out through the water-filled tunnels.
In comments released by the government, Interior Minister Anupong Paojinda said officials were meeting Monday morning about the next stage of the operation and how to extract the remaining nine people from the cave in the country's north.
Four were rescued over the weekend. Relatives were able to see them through a glass partition, the governor said.
The boys, who have not been identified, were kept away from visitors due to concerns about possible infection.
Another video from Thai PBS showed an ambulance arriving at a hospital in the city of Chiang Rai, near the cave network. The boys have reportedly yet to meet their families, though a senior official told The Guardian that they could be reunited on Monday night. "All eight are in good health, no fever. everyone is in a good mental state", Jedsada Chokdamrongsuk, permanent secretary of the public health ministry, said at Chiang Rai hospital where the boys were recuperating on Tuesday morning. One was that it was unknown how safe and dry the area where they had taken shelter would stay as Thailand's rainy season, which lasts until at least late October, picks up pace.