The Syrian countryside is seen from the air on Aug. 17, 2019. A helicopter mishap on Sunday in northeastern Syria injured 22 U.S. service members, according to U.S. Central Command. (Alec Dionne/U.S. Army)

A helicopter accident on Sunday in northeastern Syria injured 22 U.S. service members, according to U.S. Central Command.

The troops suffered “injuries of various degrees” and were receiving treatment, the command said Monday evening in a statement. Ten were evacuated to higher-care facilities outside the region.

On Tuesday, an unspecified number of troops arrived at Landstuhl Regional Medical Center in Germany, hospital spokesman Marcy Sanchez said.

Their conditions had not yet been determined, Sanchez said.

No enemy fire was reported and the accident’s cause is under investigation, according to the command.

The United States has about 900 service members in Syria, part of joint efforts with Kurdish fighters to prevent the resurgence of the Islamic State, according to the command.

The U.S. also has about 170 contractors in Syria, CENTCOM spokesman Lt. Col. Dave Eastburn said in March.

A contractor died and at least 23 troops were injured in March by a drone attack on a U.S. base by groups linked to Iran’s Revolutionary Guard. The U.S. responded with airstrikes on facilities used by the groups.

U.S. troops have been in the region since the Islamic State group swept through Iraq and Syria in 2014, taking control of large swaths of territory.