BEIRUT, Lebanon — 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 the 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 had been killed and 192 wounded in the explosions, which he called a terrorist attack. Opposition supporters said that more than 50 people had been 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.