Washington DC - Five American service members were killed when a helicopter crashed into the Mediterranean during a training exercise, US officials said Sunday.

Officials did not specify where the aircraft was flying from, but the US has deployed a carrier strike group to the Mediterranean as part of efforts to prevent the Israel-Hamas war from spiraling into a regional conflict.

"During a routine air refueling mission as part of military training, a US military aircraft carrying five service members suffered a mishap and crashed into the Mediterranean Sea.

All five of the service members onboard the aircraft were killed," the US European Command (EUCOM) said in a statement on the November 10 crash.

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President Joe Biden paid tribute to the victims in a statement from the White House.

"Our service members put their lives on the line for our country every day," Biden said.

"They willingly take risks to keep the American people safe and secure. And their daily bravery and selflessness is an enduring testament to what is best in our nation."

Defense Secretary Lloyd Austin also offered his condolences in a statement that identified the crashed aircraft as a helicopter.