The Britain-based Syrian Observatory for Human Rights (SOHR) said that the airstrike targeted south of the Daesh-held Mansurah town, located about 30 kilometers west of the provincial capital city of Raqqah, in the early hours of Tuesday.

“We can now confirm that 33 people were killed, and they were displaced civilians from Raqqah, Aleppo and Homs,” SOHR head Rami Abdel Rahman said on Wednesday.

He added, “They're still pulling bodies out of the rubble until now. Only two people were pulled out alive,” he added.

“Raqqah is Being Slaughtered Silently,” an activist group that publishes news from the Daesh-controlled Syrian city, said the targeted school hosted nearly 50 displaced families.

At least 10 civilians were killed and several others injured on March 12, when US-led military aircraft bombarded the town of Maskanah, located 100 kilometers southeast of the northwestern city of Aleppo.

The development came only two days after 30 people, including six women and eight children, lost their lives when coalition fighter jets pounded Matab al-Borashid village near Raqqah.

The US-led coalition has been conducting airstrikes against what are said to be Daesh terrorists inside Syria since September 2014 without any authorization from the Damascus government or a UN mandate.

The coalition has repeatedly been accused of targeting and killing civilians. It has also been incapable of destroying Daesh, Press TV reported.