Dozens of people were killed when an airstrike hit a school near ISIS' de facto capital of Raqqa that was sheltering refugees who had fled fighting in Palmyra, activist groups and state-run media said Wednesday.
The state-run Syrian Arab News Agency, the activist group Raqqa Is Being Slaughtered Silently and the UK-based Syrian Observatory for Human Rights all blamed the US-led coalition against ISIS for the airstrike.
In a statement, the coalition said it had "no indication that an airstrike struck civilians near Raqqa." It added, "We will provide this information to our civilian casualty team for further investigation."
The school is in the town of al-Mansoura, west of Raqqa.
The northern city of Raqqa was the first major city captured by ISIS, with its forces in full control by early 2014, and is the extremist group's operational command headquarters.
It is now largely surrounded, its main supply routes cut off by advancing forces. US-backed Kurdish and Arab forces are squeezing ISIS from the north, while Syrian government troops -- backed up by Russia -- have been pushing from the west.
The US-led coalition against ISIS has also been carrying out airstrikes against the city.