International media outlets report that according to Syrian opposition activists, almost two dozen children have reportedly been killed in an airstrike on a school complex in Syria’s Idlib province.

According to RT, the activists said that at least 28 civilians, mostly children, were killed when the strikes hit a school complex in the village of Hass on Wednesday.  

International Business Times reports that the attack took place 72 kilometers south of Aleppo around 11:30 am local time when schoolchildren were being sent home due to air raids. 

An unidentified activist from the opposition Idlib Media Centre told AFP: “One rocket hit the entrance of the school as students were leaving to go home, after the school administration decided to end classes for the day because of the raids.”

According to Euronews, a Syrian state TV report quoted a military source as saying that a number of militants had been killed when their positions were targeted in Haas, but did not mention a school.

The UN Children’s Rights & Emergency Relief Organization has condemned the tragedy as a potential “war crime,” saying it is likely the “deadliest attack on a school” since the beginning of the Syrian war.

“Twenty-two children and six teachers were reportedly murdered today when their school compound was repeatedly attacked in Idlib, Syria,” UNICEF Executive Director Anthony Lake said in a statement. He did not specify the circumstances of the attack or the sources of the reports.

Media outlets note that the attack has been blamed on Russia and comes on the same day that Amnesty International claimed some 300 civilians have been killed by the US-led coalition in Syria.

Russia’s ambassador to the United Nations, Vitaly Churkin, said that Moscow will look into the facts to determine whether a possible airstrike destroyed the school, as reports of the deadly assault have so far only been confirmed by groups with tainted reputations and questionable sources.

Russian Foreign Ministry has said that Russia was not involved in an airstrike on the school complex in Idlib province.

“Everyone has accused Russia and Syrian forces of the attack, saying directly that it was a bombardment carried out by Russia and Syria.  This is a lie.  Russia has nothing to do with this dreadful attack,” Russian Foreign Ministry spokeswoman Maria Zakharova said in a statement.

The latest bulletin from the Russian Center for Reconciliation doesn’t mention any operations in Idlib province.

The ministry said that it is investigating the data in connection with the Idlib attack.

Russia “calls upon all international organizations to join the investigation” into the incident, Zakharova said.