(RNN) – A volunteer diver has died in Thailand as rescue teams work to save 12 boys and their soccer coach trapped in a cave system.
According to CNN, the man was a former Thai Navy SEAL diver, and was on his way out of the cave when he died around 2 a.m. local time.
He's been identified as Saman Kunan, 38, according to the BBC.
CNN described his cause of death as "due to a lack of air while attempting to return to a command center" inside the cave.
Officials said he was carrying out a mission to place oxygen tanks along the route between the command center and the area where the team is trapped.
"A former SEAL who volunteered to help died last night around 2 a.m. His job was to deliver oxygen. He did not have enough on his way back," said Passakorn Boonyaluck, deputy governor of the Chiang Rai province, where the Tham Luang Nang Non cave complex is located.
The soccer team has been trapped in the cave since June 23, after fierce rains raised the water level while they were inside.
British divers found all members of the team and their coach alive on Monday. A large rescue operation is now underway to get the team out.
Authorities have wrestled with possible methods for delivering them safely. One solution is to help them swim out of the flooded cave complex, a risky proposition, as demonstrated by Kunan's death – the first fatality in the rescue operation.
The risks are increased because the boys and their coach are weakened from lack of food. Some boys also don't know how to swim.
It's taken even experienced rescue divers up to five hours to safely navigate the dangerous cave channels to reach the team. Kunan's mission was to prolong the time divers could remain submerged by strategically placing oxygen tanks along the dark and narrow route.
Along with coordinating diving teams, authorities have been pumping water out of the cave, racing against heavy rains that are soon expected to hit the region.
Rescuers are trying to get the water low enough for the boys to keep their heads above it for long stretches of the way out, cutting down their reliance on scuba gear.
Still, the team has practiced wearing diving masks and breathing with scuba gear in preparation for a dive.
Officials have considered delaying the rescue until the rainy season ends, which will be four months from now.
That solution, however, now appears less likely, as authorities have expressed a greater need for urgency because of the coming rains and the dangerously low oxygen levels inside the cave.
Oxygen has gotten low because of the large number of people now in the cave. Rescuers are working to get an oxygen line to the soccer team, which will be tied to a telephone line for communicating with the team.
"We can no longer wait for all conditions [to be ready] because the circumstance is pressuring us," Thai SEAL commander Arpakorn Yookongkaew said. "We originally thought the boys can stay safe inside the cave for quite some time, but circumstances have changed. We have [a] limited amount of time."
Four SEALs, including a medic, are looking after the team in the meantime.
The rescue effort has grown into an international collaboration, with divers from the U.S. military, the U.K., China and Australia helping out.
The private sector has also gotten involved; Tesla founder Elon Musk said he's sending engineers from two of his other companies, SpaceX and the Boring Company, to the flooded cave.