LAHORE, Pakistan -- A large bomb blast ripped through a protest rally in the eastern Pakistani city of Lahore on Monday, killing at least 11 people and wounding nearly 60 in an attack claimed by a breakaway Taliban faction.

The blast occurred when a man on a motorcycle rammed into the crowd of hundreds of pharmacists, who were protesting new amendments to a law governing drug sales, local police official Zaheer Abbas said. He added that two senior police officers, including a former provincial counterterrorism chief, were among those killed.

Sameer Ahmad, the Lahore deputy commissioner, said at least 11 people were killed and 58 wounded.

A Taliban splinter group called Jamaat-ul-Ahrar claimed the attack in a text message, saying it was revenge for Pakistani military operations against Islamic militants in tribal regions along the Afghan border.

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Live TV registered a loud bang and showed smoke and fire billowing up as people ran away, some of them carrying the wounded. “We just couldn’t understand what happened,” Tufail Nabi told local Geo News TV. “It was as if some big building collapsed,” he said as he limped away.

Jamaat-ul-Ahrar is one of several splinter groups from the Pakistani Taliban, which has carried out scores of attacks against security forces and religious minorities. In recent years, Pakistan has had launched several offensives against the Taliban and other Islamic militant groups in the tribal regions.