The US Central Command has said that 22 US military personnel have been injured in a helicopter crash in northeastern Syria.

According to the Reuters news agency, US Central Command said in a statement that 10 military personnel have been transferred to an intensive care unit for medical assistance.

The Central Command, which oversees US forces in the Middle East, said Sunday’s incident was under investigation, but no enemy attack was reported.

In March, two attacks by Iranian-backed militants in Syria left 23 American soldiers with brain injuries.