Syrian Kurdish officials say Turkish shelling has hit a prison holding Islamic State militants in northeastern Syria.

A video shared by the officials Friday shows a shell landing in the courtyard of what appears to be a prison facility in the city of Qamishli. Seconds later, a handful of men open doors and seem to be trying to leave.

An official with the mostly Kurdish Syrian Democratic Forces says some of the men in the video are security guards seeking to contain the escape and regain control of the prisoners. The official spoke on condition of anonymity because he wasn’t authorized to brief the media.

It was not possible to verify the attempted escape. But chaos and the ongoing assault have raised fears that the Turkish offensive on Kurdish-held northeastern Syria may undermine the security of over two dozen facilities where 10,000 IS militants are held. There are 2,000 foreigners among them.

The Kurdish officials said Turkish shells fell near another prison facility on Friday and Wednesday in Qamishli, which is only 2 miles (3 kilometers) from the Turkish border.