Activists said forces loyal to Mr. Assad launched two airstrikes on the area at the time of the blasts, while Syrian state media said a “terrorist group” hit it with two rockets.
The scale of destruction appeared inconsistent with the rockets the rebels are known to possess.
In Washington, State Department spokeswoman Victoria Nuland blamed the Assad regime for a “despicable attack” on unarmed civilians.
“The Syrian people have already endured too much loss as a result of the Assad regime’s relentless attacks on its own people,” she told reporters on Wednesday.
Syria’s Ministry of Higher Education suspended classes and exams at all Syrian universities to offer time to mourn for those “assassinated by the treacherous terrorist hand,” the state news service reported. Minister of Higher Education Mahmoud Mualla said Mr. Assad had ordered a speedy reconstruction of the university.
Also on Wednesday, clashes erupted between rebels and pro-government Kurdish gunmen in the town of Ras al-Ayn on the Turkish border, a Turkish official said.
At least eight wounded Syrians were taken across the border to the Turkish town of Ceylanpinar for treatment. One of them died in a hospital, an official in the town said. He spoke on condition of anonymity because Turkish government rules bar civil servants from speaking to journalists without prior authorization.
• Barbara Surk reported from Beirut. Associated Press writers Zeina Karam in Beirut; Suzan Fraser in Ankara, Turkey; and Bradley Klapper in Washington contributed to this article.