UNICEF has said airstrikes from either Syrian or Russian warplanes killed at least 26 people in the rebel-held Idlib province in northwest Syria on Wednesday. Children accounted for 22 of those who died, the UN organization said.

The Syrian Civil Defense rescue workers' network's Facebook page said the raids hit a residential area. The Syrian Observatory for Human Rights said at least six air raids by suspected Russian jets hit the village of Haas. Syrian state TV quoted a military source saying militants were killed in Haas, but did not make a mention of a school.

UNICEF director Anthony Lake called the attack on the school a "tragedy" and "an outrage," adding, "And if deliberate, it is a war crime."

He said the school was "repeatedly attacked," calling this potentially the deadliest attack on a school since Syria’s civil war began five years ago.

Russia's Ambassador to the United Nations Vitaly Churkin said, "It's horrible, I hope we were not involved. It's the easiest thing for me to say no, but I'm a responsible person, so I need to see what my Ministry of Defense is going to say."

Russia supports Syrian President Bashar al-Assad in the country's civil war.

The Syrian Observatory for Human Rights estimates that 89 civilians have died in airstrikes in Idlib by Syrian and Russian forces over the past week.

More than 300,000 have been killed in Syria and more than half of Syria’s population displaced since the conflict began in March 2011.

(DW)