Rebels in Syria set several buses meant to evacuate sick and injured refugees ablaze on Sunday, BBC reported. The vehicles were on their way to the villages of Foah and Kefraya in Idlib province, according to the Syrian Observatory for Human Rights.

A majority of the residents of these villages are Shi’ite Muslims. Rebel officials claimed the arson was carried out by an angry mob, Reuters reported.

The attacks come days after forces fighting for President Bashar al-Assad reached an agreement with the rebel faction to allow evacuations from the two villages in exchange for permitting rebels and civilians to leave the eastern region of war-torn Aleppo.

Till Friday, at least 50,000 civilians were still trapped in Aleppo, though around 8,000 had been evacuated, according to the United Nations. A convoy of ambulances and buses with nearly 1,000 people had driven out of the city, which has been bombarded for many months by Syrian government forces fighting rebels.