A Syrian army airstrike on an Islamic State-controlled town in northern Syria killed at least 28 people including three children on Saturday, a monitoring group said, according to Reuters.

The Syrian Observatory for Human Rights, a UK-based organization that monitors the war via a network of activists on the ground, said 19 civilians were among the dead in the helicopter attack on al-Bab, 30 km (20 miles) northeast of Aleppo.

A U.S.-led coalition is waging a separate campaign of airstrikes against Islamic State targets in Syria, but rejects the idea of partnering with President Bashar al-Assad, who it sees as part of the problem.