An air purification system malfunctioned Wednesday on a nuclear-powered British submarine during an exercise in the Arctic, and two sailors were killed and one was injured, officials said.
The HMS Tireless was submerged under an ice cap in a joint exercise with the United States at the time of the 12:20 a.m. ET incident but surfaced quickly, according to the Ministry of Defense.
The submarine's nuclear reactor was not affected, the ministry said in a statement.
HMS Tireless is a hunter-killer submarine and does not carry nuclear missiles, the ministry said.
It was not immediately clear what went wrong with the air purification system in a forward section of the submarine, a ministry spokesman said while speaking on condition of anonymity in line with government policy.
The injured sailor was airlifted to a U.S. military hospital, the ministry said. His injuries were not described as life-threatening.