Four more boys were brought out of the flooded Thai cave they had been stranded in for more than two weeks on Monday, bringing the total to eight rescued over the past two days.
Chiang Rai acting Gov. Narongsak Osatanakorn said all four boys rescued Monday are "safe and conscious" and in a hospital.
Four ambulances were seen leaving the Thai cave site Monday. Around 5 p.m. local time (6 a.m. ET), six hours after the second phase of the operation began, the first ambulance left the cave area and headed toward a helicopter, which landed at a nearby hospital. Medics appeared to remove one person on a stretcher but hid the person's identity behind multiple white umbrellas.
Monday's operation took nine hours, two fewer than Sunday, with rescuers helped by the experience they have accumulated, Narongsak told a news conference punctuated with rounds of applause.
Narongsak said he was not sure if the remaining five people will be extracted in one or more operations.
A heavy but brief downpour hit the area Monday morning, but authorities said that did not change the water level in the cave, as workers continued to pump water out. New oxygen tanks were placed before the second stage of the rescue effort began.
Regarding Sunday's rescue, Narongsak said earlier Monday that the healthiest boys were removed first. The rescued children were taken to the hospital, and officials said early Monday that they are strong and safe but need to undergo detailed medical checks.
"This morning they said they were hungry and wanted to eat khao pad grapao," Narongsak said, referring to a Thai dish of meat fried with chili and basil and served over rice.
Thai authorities said the parents of the four boys rescued Sunday are still being kept from physical contact with them due to fear of infections. Relatives were able to see them through a glass partition.
The boys and their coach had been stranded in Tham Luang Nang Non since June 23, when they went exploring in the cave after a scrimmage. Monsoon flooding cut off their escape and prevented rescuers from finding them for almost 10 days.
Narongsak said rescuers would meet Monday evening to plan for the next operation.
"We believe that we can do even better and it will be a 100 percent success," he said.
"The divers that were assembled from many countries are proud to have conducted this operation until its success," Narongsak added. "Some of them had gone to rest. Some others are preparing for the next operation."
The perilous rescues have involved two divers accompanying each boy, all of whom have been learning to dive since July 2, when searchers found them.
Cave rescue experts have said they consider an underwater escape to be a last resort, especially with people untrained in diving.
The death Friday of a former Thai navy SEAL underscored the risks. The diver, the first fatality of the rescue effort, was working in a volunteer capacity and died on a mission to place air canisters along the passage to where the boys are, necessary for divers to safely travel the five- to six-hour route.
There were several concerns that prompted authorities to move forward with the plan to dive the boys out. 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.
The other, and perhaps more worrying, was that oxygen levels in the complex were falling close to dangerous levels.
The Associated Press contributed to this report.