A suicide bombing at a Shiite mosque on the outskirts of Pakistan’s capital, Islamabad, killed at least 31 people on Friday, authorities said. Police said more than 130 people were wounded, and warned that the death toll could rise.

The explosion struck the Imam Bargah Qasr-e-Khadijatul Kubra mosque in Islamabad’s Tarlai area shortly after Friday prayers, when mosques are typically crowded with worshippers. City officials confirmed the death toll, and emergency services rushed the injured to nearby hospitals.

A security official said the attacker was stopped at the mosque’s entrance and detonated himself before entering the building.

No group immediately claimed responsibility. Prime Minister Shehbaz Sharif condemned the attack and said those responsible would be brought to justice. Security forces have launched an investigation.

South Asia analyst Michael Kugelman said the choice of target could point to the involvement of the local Islamic State affiliate or other anti-Shiite militant groups.

It was the deadliest attack in Islamabad since a 2008 suicide truck bombing at the Marriott Hotel that killed 60 people.