PESHAWAR, Pakistan: A bomb ripped through a crowded religious school Thursday night in northwestern Pakistan, killing nine people and wounding 50, police said.

“The death toll from the blast has increased to nine,” provincial health minister Shaukat Yousafzai told AFP. Initially, six people were reported killed.

“Seven patients are in critical condition and I fear a rise in the death toll,” he said.

The explosion took place as thousands of people had gathered at the religious school ahead of Friday prayers, police officer Malik Javed said.

Another police official, Shafqat Malik, said the bomb was 5 kilograms of explosives stuffed into a canister likely set off by a timer.

There was no immediate claim of responsibility for the attack, but militants at war with the Pakistani state often have targeted houses of worship with bombs timed to kill the highest number of people. Militants often target mosques belonging to the other sect.