WASHINGTON: Twenty-two U.S. service members were injured in a helicopter "mishap" in northeast Syria, the U.S. Central Command said late on Monday.

Ten service members had been evacuated to higher care facilities outside the Central Command area of responsibility, it said in a statement. The cause of the incident on Sunday was under investigation, although no enemy fire was reported, said the U.S. Central Command, which oversees U.S. forces in the Middle East.

In March, 23 U.S. troops in Syria suffered traumatic brain injuries during two attacks by Iran-backed militants, it said in April.