BEIRUT — U.S.-led coalition air raids targeted towns and villages in northern and eastern Syria controlled by the Islamic State group, including one strike that hit a grain silo and reportedly killed civilians, activists said Monday.

Washington and its Arab allies opened their air assault against the extremist group last week, going after its military facilities, training camps, heavy weapons and oil installations. The campaign expands upon the airstrikes the United States has been conducting against the militants in Iraq since early August.

The Britain-based Syrian Observatory for Human Rights said coalition forces hit Islamic State group facilities overnight in Aleppo, Raqqa, Hassakeh and Deir el-Zour provinces. It said there were casualties, including civilians, but did not have exact figures.