The U.S.-led coalition says its Syrian allies have successfully dealt with an "incident" at a detention center in northeastern Syria which activists described as an attempted prison break by Islamic State militants.

Col. Scott Rawlinson, coalition spokesman, said Saturday all detainees were accounted for after the Syrian Democratic Forces "peacefully" dealt with the incident that broke out a day earlier. He said coalition forces supported the SDF with aerial observation.

Activists, including from Rojava Information Center, reported IS detainees in the town of Derik attempted the escape.

The Kurdish-led SDF is holding hundreds of foreign IS militants in facilities around areas they control in northeast Syria. Many more local suspects are detained separately. It was not clear if the attempted break out was among foreign or local detainees.