DAMASCUS, Syria — Three suicide bombers detonated their explosives-packed cars near an officers' club in Syria's northern city of Aleppo on Wednesday, killing at least 31 people and causing massive destruction that trapped scores under the rubble, Syrian state media and activists said.

The blasts went off at a main square in a government-controlled district of the city, while a fourth explosion detonated a few hundred meters (yards) away near the Chamber of Commerce, they said.

Aleppo, Syria's commercial hub and largest city, has seen intensified fighting between regime forces and rebels trying to oust President Bashar Assad, especially after the fighters launched a new offensive last week. But it has not been the target of frequent suicide attacks, and Wednesday's stunning wave of explosions caused panic and fear among residents.