An explosion inside a mosque killed at least 32 people and wounded about 150 more in Pakistan’s northwestern city of Peshawar, a government official said, adding many of the casualties were police officers who had gathered for noon prayers.

The mosque is located within a compound that includes the headquarters of the provincial police force and a counterterrorism department, Peshawar’s police chief Ijaz Khan said on Monday.

The possibility of a suicide bombing could not be ruled out, he said, adding that traces of explosives were found inside the mosque.

No one has yet claimed responsibility for the blast, which ripped through the crowded mosque, causing a wall to collapse.

The building is located in a highly fortified area of the city. There were at least 260 people inside, police official Sikandar Khan said.

“A portion of the building had collapsed and several people are believed to be under it,” he added.