Some 17 children were among more than 20 civilians killed when an air strike hit a school in the Syrian province of Idlib on Wednesday (26 October), activists have said.

The attack took place 45 miles (72km) south of Aleppo in the village of Hass, around 11.30am local time (8.30am BST) when schoolchildren were being sent home due to air raids. According to eye-witnesses, one explosion took place at the school entrance just as children were leaving.

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Several victims have been critically injured and the death toll is expected to rise.

Videos and images circulating on social media showed dead and injured children as the Syrian White Helmets (SCD) searched the rubble for survivors.

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.

Rami Abdel Rahman, head of the UK-based Syrian Observatory for Human Rights (SOHR), was quoted by Al Jazeera as saying: "the dead children are students and the planes are believed to be Russian".

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."

Syrian regime forces loyal to President Bashar al-Assad and their Russian allies have been regularly accused of indiscriminately killing civilians, many of them around the besieged city of Aleppo, and targeting humanitarian aid convoys and hospitals.

Russia says it is only attacking Islamist groups including Isis and the ongoing crisis has soured relations between the Kremlin and Washington.

However the US-led coalition has also been regularly accused of killing civilians in both Syria and neighbouring Iraq. Amnesty International said on Wednesday that the coalition had killed hundreds of civilians in Syria, many of them in the battle for Manbij in July 2016.

Neil Sammonds, Amnesty International's researcher for Syria, told The Guardian: "In its backing of anti-Isis ground forces during this summer's Manbij campaign, the US-led coalition killed some 250 or more civilians, and yet it does not acknowledge them."