The UN children’s agency UNICEF has confirmed that 22 children were killed in airstrikes on a school complex in Syria’s rebel-held Idlib province Wednesday. Earlier reports had put the death toll at 12. At least six teachers were also killed in the attack. UNICEF Director Anthony Lake told AFP the school was “repeatedly attacked,” noting that it may be the deadliest attack on a school since the start of the civil war five years ago. “This is a tragedy. It is an outrage. And if deliberate, it is a war crime,” Lake was quoted as saying. The Syrian Observatory for Human Rights said there were six attacks carried out by “either Russian or Syrian” warplanes. Russia’s UN ambassador Vitaly Churkin had little to say when asked about Russia’s involvement: “It’s horrible, horrible. I hope we were not involved.” The strikes hit just as students were leaving the school after teachers decided to release them early due to air raids in the area.