A bomb blast hit a bus convoy waiting to cross into government-held Aleppo in Syria on Saturday, killing and wounding dozens of people evacuated from two Shi'ite villages the day before in a deal between warring sides.
The agreement had stalled, leaving thousands of people from both government-besieged and rebel-besieged areas stranded at two transit points on the city's outskirts, before the explosion occurred.
Late on Saturday buses from the convoy hit by the bombing began crossing into government-held territory as the deal resumed, pro-Damascus media outlets reported.
But the incident underscored the difficulty carrying out any agreement between warring sides in a volatile and complex Syrian conflict which, in its seventh year, shows no signs of easing.
A media unit run by Damascus ally Hezbollah said the attack was carried out by a suicide car bomb and killed at least 40 people. The Observatory said more than 24 were killed.
Footage on state TV showed bodies lying next to charred buses with their windows blown out, and vehicles in flames.