(This Dec. 12 story has been refiled to correct temperature conversion in last paragraph.)

FILE PHOTO: General view of McMurdo Station operated by the United States on Antarctica. Picture taken January 1 2000./File Photo

(Reuters) - Two technicians performing maintenance at a U.S. research station in Antarctica died on Wednesday while working on a building that houses a generator for a nearby radio transmitter, the National Science Foundation (NSF) said.

The pair, both employed as subcontractors at the NSF-managed McMurdo Station in Antarctica, were found unconscious on the floor of the building after a helicopter pilot flying over the area saw what appeared to be smoke coming from the structure and landed to investigate.

One of the technicians was pronounced dead by medical personnel called to the scene. The other was pronounced dead a short time after being flown to the McMurdo medical clinic, the NSF said in a statement.

The two workers, described as fire technicians, were performing preventive maintenance on the building’s fire-suppression system before they were found, the agency said.

No further details were immediately provided, and the incident was under investigation, the foundation said.

The NSF said it was not releasing any personal information about the two workers, except to say they were employed by a Virginia-based company, PAE, which in turn was hired by the U.S. Antarctica Program’s logistics contractor Leidos, headquartered in Colorado.

The research station, established by the United States in 1955, is situated near Antarctica’s McMurdo Sound, named for a British naval officer who was part of the expedition that first charted the area in 1841.

The largest outpost in Antarctica, it lies at the tip of Ross Island in the New Zealand-claimed territory known as the Ross Dependency. The incident in question occurred on Dec. 12 local time, which goes by New Zealand time.

Daytime highs in December, in the middle of the Antarctic summer, average 31.5 degrees Fahrenheit or minus 0.3 degrees Celsius. More than 1,000 people, including scientists and support personnel, work at the station this time of year.