BEIRUT -- A suspected U.S.-led coalition airstrike on a northern Syrian village killed seven members of the same family, activists said Saturday.

Arshaf, held by Islamic State militants, lies near the front lines of the war between the extremist group and U.S.-backed Syrian rebels. Recent advances by the rebels, backed by coalition airstrikes, have eaten away at IS territory near the Turkish border.

The Syrian Observatory for Human Rights, a Britain-based group that monitors the Syria conflict through local observers, said the planes responsible for the Arshaf strikes were seen to cross into Syrian airspace from Turkey. It said the strikes killed seven family members, among them five women and a child.

The Local Coordination Committees activist network said 10 people were killed.

Arshaf lies 8 kilometres from the contested town of Marea, north of the city of Aleppo.

To the east, in the city of Raqqa, where the extremist group has maintained its de facto capital since 2014, mosques broadcast an announcement that civilians would be allowed to leave the city to the countryside, after planes thought to belong to the international coalition dropped flyers on the city instructing residents to leave, a local group reported.

The group Raqqa Is Being Slaughtered Silently, which smuggles information out of the IS territory, said the illustrated flyers, scattered over the city Thursday and Friday, show a family fleeing a dark, urban war zone where three IS militants appear to lie dead by the side of the road to a sun-lit, hilly, green countryside scene. "The time you have been waiting for has arrived. It is time to depart Raqqa," the flyer says.