The United States Central Command announced a “helicopter mishap in northeastern Syria” left 22 U.S. service members injured from the accident. According to CENTCOM, the injuries suffered were “of various degrees” of seriousness.

“The service members are receiving treatment for their injuries and 10 have been evacuated to higher care facilities outside of the CENTCOM [area of responsibility],” CENTCOM said in a press release. The cause of the incident is under investigation, although no enemy fire was reported.

U.S. forces have been in Syria since 2015 to advise and assist the Kurdish-led Syrian Democratic Forces in the fight against the militant Islamic State group. There are at least 900 U.S. forces in Syria on average, along with an undisclosed number of contractors.

A spokesman for the Kurdish forces did not immediately respond to an Associated Press request for comment.

Sunday’s accident in Syria followed multiple helicopter-related incidents on U.S. soil in 2023. Two U.S. Army helicopters collided and crashed in Alaska on Thursday, April 27, while returning from a training flight.

Three soldiers were killed in the collision. It was the second crash involving military helicopters in Alaska in 2023, after two soldiers were injured in a  rollover accident.

Nine people died after two Blackhawk helicopters crashed during a training exercise near Kentucky’s border with Tennessee on Wednesday, March 29. Like with the Syria and Alaska helicopter accidents, a cause of the Kentucky crash was not immediately clear.