A Syrian Democratic Forces (SDF) fighter poses for a picture near Euphrates River, north of Raqqa city, Syria March 8, 2017.

Three hundred families of ISIS fighters have fled the extremists’ self-proclaimed Syrian capital of Raqqa in 24 hours, as rival forces encircle the city, activists said Saturday.

The pro-opposition Syrian Observatory for Human Rights said “300 families of foreign fighters of ISIS have left the city of Raqqa since dawn Friday to take refuge in the province of Deir al-Zor to the east and Hama to the west.”

The northern city of Raqqa is the target of advancing Turkish-backed Syrian rebels, a U.S.-backed alliance of Kurdish and Arab forces as well as Syrian government troops supported by Russia.

The Britain-based Observatory’s head, Rami Abdel-Rahman, said that ISIS families were using the only remaining escape route, on boats across the Euphrates River to the south.

The US-led coalition has been pounding the Raqqa area regularly for months.