(CNN) — As the first members of the boys’ soccer team trapped in a cave in Thailand were rescued Sunday, the focus begins to shift to the boys’ long-term health and getting them proper medical aid.

Oxygen is a top priority. Health experts said, authorities would first be checking the rescued boys’ exposure to a lack of oxygen while in the cave.

Thai officials on Friday said oxygen levels in the cave air plummeted dangerously to just 15%.

“One of the major concerns is oxygen right now. They’ve been in an area where oxygen levels are low,” Dr. Darria Long Gillespie of the University of Tennessee School of Medicine told CNN. “As soon as they get out, that’s what they’ll be checking: their oxygen levels and their breathing.”

They will also be checked for malnutrition, dehydration and an array of other health effects.

Dr. Carole Lieberman, a psychiatrist who is also a scuba diver, said it would be extremely important to relay the good news of the first boys’ rescue to the others who remain trapped inside. “That would be such a boost for their confidence,” she said.

The rescue is two-pronged: to help the boys who have been brought out of the cave, while working to save the remaining boys and coach still trapped inside.

The rescue operation, authorities said, has paused for the night.

Authorities said oxygen tanks needed to be refilled before continuing.