Dozens Of Civilians Killed Near Raqqa In Airstrike Activists Blame On Coalition : The Two-Way Monitor groups allege a strike by U.S.-led forces leveled a school near ISIS' de facto capital in Syria. The coalition says there's no indication it was responsible but it will investigate.

Dozens Of Civilians Killed Near Raqqa In Airstrike Activists Blame On Coalition

An airstrike by U.S.-led coalition forces leveled a school west of Raqqa and killed at least 33 people, according to two activist groups monitoring Syria. The groups allege the attack, which they say occurred overnight on Monday and Tuesday, hit a building that had been housing families fleeing violence in war-torn areas nearby.

According to one of those groups, Raqqa is Being Slaughtered Silently, the fate of 50 families who had been in the school in the village of Mansoura remains unknown. Both Raqqa and Mansoura are under the control of the Islamic State, which counts Raqqa as the de facto capital of its territorial claims.

"We can now confirm that 33 people were killed, and they were displaced civilians from Raqqa, Aleppo and Homs," Rami Abdel Rahman, director of the U.K.-based Syrian Observatory for Human Rights, told the French news service Agence France-Presse. "They're still pulling bodies out of the rubble until now. Only two people were pulled out alive."

In a statement, the coalition forces cast doubt on these accounts, saying that while they "routinely strike [Islamic State] targets in this area," they "have no indication that an airstrike struck civilians near Raqqah as the Syrian Observatory for Human Rights claims."

That said, the coalition pledged that "since we have conducted several strikes near Raqqa we will provide this information to our civilian casualty team for further investigation."

"Coalition forces work diligently to be precise in our airstrikes," the group added. "Coalition forces comply with the Law of Armed Conflict and take all feasible precautions during the planning and execution of airstrikes to reduce the risk of harm to civilians."

The allegations of civilian deaths follow a similarly bloody incident just days ago, in which locals allege a U.S. airstrike killed at least 30 people at a small mosque compound in rebel-held northern Syria.

"If you look at photographs and videos of the scene, a huge crater is all that's left of the building that was targeted," NPR's Alice Fordham told All Things Considered, describing the strike last Thursday.

Syrian witnesses of that incident say it was the regular meeting of a peaceful religious group, with dozens of civilians, while the Pentagon says "they are confident that the building that they hit was being used by al-Qaida for a meeting," Alice reported last week.

The bloodshed comes as U.S.-backed rebels kicked off a significant offensive to dislodge ISIS militants from Syria's Tabqah Dam, which is very close to the alleged airstrike in Mansoura. That offensive, led by the Syrian Democratic Forces, began overnight with the support of U.S. helicopters, artillery and logistical assistance.