Amateur video uploaded to the internet on Tuesday (January 15) showed the moment a second explosion ripped through Aleppo University, killing at least 52 people and wounding dozens, according to the Syrian Observatory for Human Rights.
The twin blasts shook the university on the first day of student exams.
The video shows smoke streaming from the side of a building, purportedly a result of the first blast, before a loud explosion is heard and dozens of students flee the area.
A second plume of heavy smoke can then be seen streaming from the side of the building after the explosion.
The content of the footage, obtained from a social media website, could not be verified.
Some activists in Aleppo said a government attack caused the explosions, while state television accused "terrorists" - a term they often use to describe the rebels - of firing two rockets at the school. A rebel fighter said the blasts appeared to have been caused by "ground-to-ground" missiles.
The nearest rebel-controlled area, Bustan al-Qasr, is more than a mile away from the university.
Bloodshed has disrupted civilian life across Syria since a violent government crackdown in early 2011 on peaceful demonstrations for democratic reform turned the unrest into an armed insurgency bent on overthrowing President Bashar al-Assad.
More than 50 countries asked the United Nations Security Council on Tuesday (January 15) to refer the crisis to the International Criminal Court, which prosecutes people for genocide and war crimes. But Russia - Assad's long-standing ally and arms supplier - blocked the initiative, calling it "ill-timed and counterproductive."