The US military has confirmed that 10 crew members died in a collision between two of their helicopters off the coast of Djibouti on Friday.
A spokesman for the US military in the Horn of Africa also confirmed that two of the 12-man crew were rescued.
The CH53 marine transport helicopters were based on Camp Lemonier, a French military base in Djibouti.
The cause of the crash is not yet known but is not believed to be hostile, a US defence spokesman said earlier.
Names withheld
The Djibouti facility serves as a headquarters for a US military operation aimed at stopping militant groups infiltrating the Horn of Africa and the Red Sea.
A search was initially launched for the 10 missing crew members, but was called off on Saturday.
The dead troops included US Marines and two Air Force airmen, according to a statement by the US-led Combined Joint Task Force Horn of Africa.
"Our deepest sympathy and heartfelt prayers go out to the family members, friends, loved ones and co-workers of our fallen brothers-and sisters-in-arms," said Maj Gen Timothy Ghormley, commanding general of the counter-terrorism force.
"We mourn their loss and honour their memory."
Relatives had been notified, but names of those killed were being withheld, according to the statement.
The two rescued crew members were said to be in a stable condition on Saturday after being flow to the US military's Landstuhl Regional Medical Centre in southern Germany
The cause of the crash is being investigated.
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