Islamic State prisoners on Sunday seized control of the ground floor of a major prison in northeastern Syria run by the U.S.- backed Syrian Democratic Forces (SDF), with some of the militants managing to escape, an SDF spokesman said.
The SDF, which is spearheaded by the Kurdish YPG militia, mounted an operation to capture those who fled as security forces sent reinforcements to crush the mutiny in Hasaka prison, spokesman Mustafa Bali said in a tweet.
"The situation is tense inside the prison currently and we sent anti-terror forces and additional troops to control the situation," Bali said.
Earlier, Syrian state television said 12 militants had fled from the prison towards the southern outskirts of Hasaka.
A U.S. led coalition spokesman confirmed a riot had taken place, adding the facility held only low-level Islamic State members.