BEIRUT — At least two deadly explosions, possibly caused by airstrikes or bombs, devastated the campus of Aleppo University in Syria on Tuesday as students were taking exams, a major escalation of the violent struggle for control of the country’s largest city. The opposition and government blamed each other for the blasts, among the worst since the Syrian conflict began nearly two years ago.
Syria’s ambassador to the United Nations, Bashar Jaafari, said at a Security Council meeting that 82 people were killed and 192 wounded in the explosions, which he called a terrorist attack. Opposition sympathizers said more than 50 people were killed.
The carnage at the public university, the premier educational institution in Aleppo, shocked Syrians inured to violence and brought an unusually intense round of speculation and mutual recrimination.
The toll was extraordinarily high even for Syria’s bloody conflict. The target was mysterious. The university has been a center of antigovernment demonstrations but is in a government-held area, so neither side had an obvious reason to strike. And there was horror that the explosions struck as students tried to go about their studies normally, even after people who had fled the fighting in other Aleppo neighborhoods had taken up residence in a dormitory, which was hit by a blast.
''The most painful scene was a chopped hand with a pen and notebook right next to it,’’ an education student who identified himself as Abu Tayem said over Skype.
The university’s press office appeared to have issued a statement accusing Syrian air force MiG fighter planes of targeting the campus in two missile attacks three minutes apart, destroying buildings and causing ‘‘massive destruction in the surrounding roads.’’ The statement denounced the attacks as a ‘‘criminal act.’’
But it was unclear if the statement, which was posted on an opposition Facebook page, reflected the view of the leadership of the government-run university.
The government, too, appeared to realize the impact of the event, issuing an unusual statement casting President Bashar Assad as coming to the school’s rescue. The Education Ministry said in a statement that the president would oversee reconstruction ‘‘immediately to secure the functioning of the teaching process.’’
Aleppo, in northern Syria, has essentially been a battleground since July. But the campus area had been largely spared until Tuesday.
Competing and contradictory accounts proliferated in a propaganda battle to cast blame for the explosions, none of them verifiable because of the difficulties of firsthand reporting inside Syria. Some witnesses reported hearing the screech of warplane jet engines, but there was no corroborating video.
The Syrian Observatory for Human Rights, an antigovernment group based in Britain with a network of contacts in Syria, said that either government airstrikes or car bombs could have been responsible. Car bombs have been used by some rebel groups, and a rebel battalion immediately accused the Syrian Observatory on Facebook of ‘‘supporting the lies of the regime.’’
One student said insurgent fighters just outside Aleppo who apparently were armed with a heat-seeking missile fired it at a fighter; when the fighter pilot dropped a heat balloon as an evasive tactic, the missile followed the balloon and then exploded near a military post adjacent to the university dormitories. That account, however, did not explain the second explosion.
Other students also reported seeing what they described as heat balloons before the explosions. Some said the university dormitories were hit by one missile, and that other missiles struck the buildings that house the university’s architecture and humanities departments.
Witness accounts and videos uploaded on the Internet from the campus and nearby hospital painted a picture of utter panic.
''I was inside my car when I heard the sound of two consecutive explosions which was preceded by the sound of a warplane,’’ said an antigovernment activist in Aleppo reached on his mobile telephone, who identified himself only by his first name, Tony.