An investigation is underway after two fire technicians at a US research station in Antarctica have died after they were discovered when smoke was spotted coming from the building they were in.

The pair, who worked at the McMurdo Station in Antarctica, were found unconscious on the floor of the building after a helicopter pilot flying over the area saw the smoke and landed to investigate.

The men had been performing preventive maintenance on a fire suppression system at a radio transmitter generator, the National Science Foundation (NSF) said.

Both were given CPR but one was pronounced dead at the scene by medical staff from the McMurdo clinic, and the other was pronounced dead after being flown to the clinic on Ross Island, the NSF said. Their relatives have been notified.

The foundation said the deaths were under investigation.

The workers were employed by a Virginia-based company, PAE, which in turn was hired by the US Antarctic Programme’s logistics contractor Leidos, based in Colorado.

The McMurdo research station, established by the US in 1955, is named after Archibald McMurdo, a British naval officer who was part of the expedition that first charted the area in 1841.

It lies on the southern tip of Ross Island in the New Zealand-claimed territory known as the Ross Dependency, used as a base for expeditions to the South Pole.

The buildings at the station are ageing and need replacing, but with the Trump administration seeking to slash federal spending, the fate of Antarctic research may be in doubt.

Daytime highs in December, in the middle of the Antarctic summer, average -3C. More than 1,000 people, including scientists and support personnel, work at the station at this time of year.

Leidos said its Antarctic team provides “station operations, logistics, information technology, construction, maintenance and more”.

Journey to Antarctica Show all 8 1 /8 Journey to Antarctica Journey to Antarctica Penguins on Curverville Island Reuters Journey to Antarctica Seals on a beach in Half Moon Bay Reuters Journey to Antarctica Penguins in Neko Harbour Reuters Journey to Antarctica A Greenpeace boat sails in Andvord Bay Reuters Journey to Antarctica An iceberg floats in Selvick Cove Reuters Journey to Antarctica A krill fishing ship with unknown nationality in Half Moon Bay Reuters Journey to Antarctica Waves break on Greenpeace ship ‘Arctic Sunrise’ at the Drake Passage Reuters Journey to Antarctica A whale swims in Selvick Cove Reuters

Joseph Dantona, a volunteer firefighter, tweeted: “Very sad news… The work of all in Antarctica is not without risk, often significant risk – please know that there are a great many who appreciate such dedication and commitment.”

Additional reporting by agencies