NEW YORK (AP) — The National Science Foundation says two technicians working on a fire-suppression system at an Antarctica scientific station were found unconscious and died.

The foundation said Wednesday the two had been working in a building at McMurdo Station, which is on Ross Island. It says they were found on the floor by a helicopter pilot who had landed after spotting what appeared to be smoke from the building.

Both were taken from the building and given CPR. One died at the scene. The other was flown to a clinic and pronounced dead shortly after. It happened Tuesday Eastern time.

They were employed by a Virginia-based subcontractor. The foundation says it is not immediately releasing any personal information about the pair. The deaths are under investigation.