DAMASCUS, Syria – The death toll from a bomb attack on a crowded bus convoy outside Aleppo has reached at least 126 in the deadliest such incident in Syria in almost a year, human rights groups reported on Sunday.

Human rights groups and United Nations agencies cited reports that more than 60 children were among the dead.

Syrian rescue workers of the Civil Defense said that they had taken away at least 100 bodies from the site of Saturday’s blast, which hit buses carrying Syrian Shia residents as they waited to cross from rebel into government territory in an evacuation deal between the warring sides.

The British-based Syrian Observatory for Human Rights said the number was expected to rise.

Those killed were mostly residents of the villages of al-Foua and Kefraya in Idlib province.

There was no immediate claim of responsibility for the attack, which the Syrian government media said was carried out by a suicide car bomber.

The Free Syrian Army, a faction of the rebel fighters described the bombing as a “treacherous terrorist attack”.

Pope Francis, in an Easter message, also condemned the attack, describing it as “ignoble”, and asking God to bring healing and comfort to what he called the “beloved and martyred Syria”.

The convoy was carrying at least 5,000 people including civilians and several hundred pro-government fighters, who were granted safe passage out of the two Shia villages which are besieged by the militants.

Under the evacuation deal, more than 2,000 people, including rebel fighters, were granted safe passage out of Madaya, a town near Damascus under government forces control.

That convoy was waiting at a bus garage in a government-held area on Aleppo’s outskirts, a few miles from where the attack took place. Madaya evacuees said they heard the blast.