A bus sits damaged after the attack outside Aleppo, Syria at the weekend.
Opposition leaders had allowed the villagers to evacuate as part of a deal with the Syrian government to give 2,000 people, including rebel fighters, safe passage out of a town near Damascus that is surrounded by government troops.
The exact reasons for the delay in completing the evacuation deal were also unclear.
It's not clear, according to Sinjab, precisely who is responsible for the blast, although there is speculation regarding just how the vehicle was able to get so close to the convoy without having had government permission.
The blast occurred at a time when the Syrian government was implementing an internationally-brokered evacuation deal, reached between the rebels and the government under the supervision of Iran, Turkey and Qatar, created to secure from the two towns as well as Zabadani and Madaya, near the capital Damascus.
Mohammad Darwish, a doctor who has been evacuated from Madaya, witnessed the explosion. Abdurrahman said no permission was given for the evacuation to go ahead while Mahmoud said it has been delayed for "logistical reasons".
Unfortunately, many of them didn't make it there alive and survivors were left stranded in the area for several hours after the attack.
It said a petrol station at the transit point was caught up in the explosion, adding to the number of victims.
A spokesman for the leading rebel faction Ahrar al-Sham said one-third of the casualties were rebels accompanying the convoy.
Death toll in bomb attack on Syria evacuees rises to 112. "We're sad and angry about what has happened".
The remainder of the dead were aid workers and rebels tasked with guarding the buses, the Britain-based group said. The two towns rebelled against Damascus' authority in 2011 when demonstrations swept through the country demanding the end of President Bashar Assad's rule. Both came under government siege in the ensuing civil war.
Foua and Kfraya, besieged by the rebels, lived under a steady hail of rockets and mortars.
Critics say the string of evacuations, which could see some 30,000 people moved across battle lines over the next 60 days, amounts to forced displacement along political and sectarian lines.
The U.S. embassy in Syria tweeted, "The United States strongly condemns today's barbaric attacks against innocent civilians, including women & children, in northern Syria".
Civil team members try to extinguish the blaze Saturday near Aleppo.