Syrian government helicopters and warplanes carried out a series of airstrikes overnight on a northern town controlled by the Islamic State group, killing at least 21 people, activists said Sunday.

The air raids struck the town of al-Bab in Aleppo province late Saturday and lasted through early Sunday morning. The Aleppo Media Center activist collective and the Britain-based Syrian Observatory for Human Rights both reported the attacks.

Observatory director Rami Abdurrahman said there were 10 strikes in total, including seven so-called barrel bombs dropped from helicopters. He said at least 21 people were killed and more than 100 wounded. […]