At least 43 persons were killed on Saturday when a car bomb struck an area near the northern Syrian city of Aleppo where an evacuation operation was underway.
According to Xinhua news agency, 48 persons were also wounded in the blast which targeted the rebel-held Rashideen area in the countryside of Aleppo province.
The explosion took place at the gathering point of buses transporting Shias evacuating from two pro-government towns in northern Syria. It was carried out by a suicide bomber driving a booby-trapped potato truck.
The buses carrying 5,000 Shias were waiting the reactivation of a deal designed to secure their transportation to government-controlled area in Aleppo.
The deal, reached between the rebels and the government under the supervision of Iran, Turkey and Qatar, was designed to secure the evacuation of the people from the pro-government Shia towns of Kafraya and Foa in Idlib province towards areas in Aleppo province.
In return, the government will allow rebels and their families to leave the rebel-held towns of Madaya and Zabadani in northern Damascus to reach Idlib province.
The evacuation started on Friday, with 5,000 Shias leaving Kafaraya and Foa and 2,300 rebels and their families leaving the town of Madaya as first batches, the report said.
The Shias reached the rebel-held town of Rashideen, while the rebels reached the government-controlled Ramouseh crossing in Aleppo.
Both convoys were set to leave to their respective destinations, before the rebels in Rashideen held the convoy of the Shias, adding new demands to the original deal.
The rebel convoy was also stuck at Ramouseh, amid reports that communications were underway to continue the implementation of the deal.
A source told Xinhua that the rebels' new demand was the evacuation of the Shia fighters first from Kafraya and Foa, before the civilians.
But the demand was rejected.
An eye witness from those waiting in Rashideen said three people with medical conditions died while waiting, before the explosion.
He added that three women gave birth inside the busses amid tough humanitarian situation as those people have been waiting there for 24 hours without enough food or water.