Twenty-two US service members were injured in a helicopter "mishap" in northeast Syria on Sunday, the US military said late on Monday, without disclosing the cause of the incident or detailing the severity of the injuries.
According to international media reports, the US military's Central Command said 10 service members were evacuated to higher-level care facilities outside the region.
Central Command, which oversees US troops in the Middle East, said no enemy fire was reported but added that the cause of the incident was under investigation.
Officials at US Central Command did not immediately respond to requests for further information.
About 900 US personnel are deployed to Syria, most of them in the east, as part of a mission fighting the remnants of Daesh.
On March, 25 US troops were wounded in strikes and counter-strikes in Syria, killing one US contractor and injuring another.
US forces first deployed into Syria during the Obama administration's campaign against Daesh, partnering with a Kurdish-led group called the Syrian Democratic Forces.
