At least 15 people were killed on Friday by suspected U.S.-led air strike on Syria's northern province of al-Raqqa, the de facto capital of the Islamic State (IS) group, a monitor group reported.
The warplanes, believed to be from the U.S.-led anti-terror coalition, struck areas in the town of Dahham in the northeastern countryside of al-Raqqa, said the Syrian Observatory for Human Rights.
The UK-based watchdog group said the death toll could likely rise due to the large number of wounded people.
It wasn't the first U.S.-led air strike that leads to civilian casualties, as the United States itself admitted before that civilian victims may have fallen during the coalition's air strikes, which has started targeting the IS positions in Syria since 2014.
In January, 2014, the IS took over al-Raqqa and declared it their de facto capital.