Amateur video obtained by euronews purports to show Syrian rebels shelling two Aleppo airports on Monday in retaliation for army helicopters dropping improvised “barrel bombs” on several parts of the city over the weekend, killing 42 people.

Euronews can not independently verify the content of the images which many people may find upsetting.

In the video, an unidentified man speaking Arabic is heard to say: “In the name of God, mercy to our martyrs. Freedom for our prisoners. The mujahidin of the Islamic Front – al-Tawhid brigade is going to shell the al-Nairab and Aleppo International Airports as a reaction to the regime forces massacre in Aleppo by explosive barrels.’‘

Barrel bombs are explosive-filled oil drums often rolled out of the back of helicopters with little attempt at hitting a particular target. They are capable of causing widespread casualties and significant damage.

Human Rights Watch (HRW) said in a report over the weekend that barrel bomb attacks had killed scores of civilians in Aleppo in the last month. It described the attacks as illegal and said they had hit residential and shopping areas.

“The Syrian air force is either criminally incompetent, doesn’t care whether it kills scores of civilians, or deliberately targets civilian areas,” HRW senior emergency researcher Ole Solvang said in the report.

Meanwhile at least 20 people were killed after a suicide bomber exploded a device near a primary school in the predominantly Shiite town of Umm al-Amed in Homs province.

Seven of the dead were children, according to the British-based Syrian Observatory for Human Rights.

Syria’s state news agency also put the death toll at 20 but said six children had died.

There was no immediate explanation for the discrepancy in the number of child casualties.

In rural Idlib, another amateur video appears to show a barrel bomb explosion and people attempting to drag victims out of rubble, many of them children.