Four huge explosions struck a government-held district of Aleppo, Syria, today, shearing off the fronts of two tall buildings, killing more than 40 people and filling the streets with rubble in a square near the area’s public park, according to video, photographs and reports from the Syrian government and its opponents.

Three explosions, which both sides said appeared to be car bombs, struck Saadallah al-Jabri Square, near the government owned Siahi, or Tourist, Hotel, which residents said had housed pro-government militiamen. Also in the area, residents said, were an officers’ club and other military and government buildings. A fourth explosion struck near the chamber of commerce in nearby Bab Jenine, both sides reported.

There was no immediate claim of responsibility for the bombings, which came after several days of heated battles in Aleppo, Syria’s largest city. But the government blamed its opponents.

The British-based Syrian Observatory for Human Rights, which relies on a network of observers inside Syria, said most of the dead were from the security forces and that the explosions went off after clashes between gunmen and guards at the officers’ club. Citing medical sources, the observatory said 90 people were wounded.

An anti-government group at Aleppo University posted a statement suggesting the target had been the Syrian president, Bashar Assad, who, according to reports in a pro- Syrian Lebanese newspaper, had visited Aleppo and ordered tens of thousands more troops to move there from the city of Hama. But official Syrian media did not mention a visit.

The bombings coincided with a spike in fighting that has brought a new level of destruction to Aleppo and its treasured medieval old city. In recent days, a large swath of the city’s ancient market was burned, and fighting spread to areas that had been stable, with rebels attacking the central municipal building and clashes erupting in once-quiet Christian and Kurdish neighborhoods.

The new fighting caused anguish for both supporters and opponents of the government. The bombings today hit a central square bordered by a graceful public garden, a downtown district full of hotels and offices, and the Christian neighborhood of Aziziyeh, where many people had sought refuge over the weekend.

Activists also reported that the al-Hal spice market near the site of the bombings was being shelled. Dozens were wounded and people were trapped there by the fighting, activists said.