The U.S. military said Monday a ‘helicopter mishap’ in northeastern Syria injured 22 service members.

U.S. Central Command said in a statement there was no enemy fire reported and the cause of the incident was under investigation.

It said 10 of those injured were taken for treatment at higher-care facilities outside of the region overseen by CENTCOM, which stretches from Egypt to Kazakhstan.

The United States has about 900 troops in Syria as part of a mission to advise and assist partners in the fight against the Islamic State group.

Some information for this report came from The Associated Press