A suicide bomber detonated explosives during crowded prayers at a mosque inside a police compound in Pakistan on Monday, causing the roof to cave in. At least 34 people were killed and 150 wounded, officials said.

Most of the casualties were police officers. It was not clear how the bomber was able to slip into the walled compound, which houses the northwestern city of Peshawar’s police headquarters and is itself located in a high-security zone with other government buildings.

Sarbakaf Mohmand, a commander for the Pakistani Taliban, claimed responsibility for the attack on Twitter. The main spokesman for the militant group was not immediately available for comment.

Pakistan, which is mostly Sunni Muslim, has seen a surge in militant attacks since November, when the Pakistani Taliban ended their cease-fire with government forces. Monday’s assault on a Sunni mosque was one of the deadliest attacks on security forces in recent years.

More than 300 worshippers were praying inside the mosque, with more approaching, when the bomber set off his explosives vest. Many were injured when the roof came down, according to Zafar Khan, a local police officer.

Worshippers Trapped Under Rubble

Rescuers scrambled to remove mounds of debris from the mosque grounds to reach worshippers still trapped under the rubble, police said.

Meena Gul, who was inside the mosque when the bomb went off, said he doesn’t know how he survived unhurt. The 38-year-old police officer said he could hear cries and screams after the blast.

Siddique Khan, a police official, said the death toll rose to 34, and the dead included Noor-ul-Amin, the prayer leader. He said the attacker blew himself up while among the worshippers.

Peshawar police chief Ijaz Khan said at least 150 were wounded. A nearby hospital listed many of the wounded in critical condition, raising concerns the death toll could still rise.

Peshawar is the capital of Khyber Pakhtunkhwa province, where the Pakistani Taliban have a strong presence, and the city has been the scene of frequent militant attacks.

The militant group, also known as Tehreek-e-Taliban Pakistan or TTP, has waged an insurgency in Pakistan over the past 15 years. It seeks the stricter enforcement of Islamic laws, the release of their members who are in government custody and a reduction in the Pakistani military presence in areas of Khyber Pakhtunkhwa province that it has longed used as its base.

The group is separate from but a close ally of the Afghan Taliban, who seized power in neighboring Afghanistan in August 2021 as U.S. and NATO troops pulled out of the country after 20 years of war.

The government’s truce with the TTP ended as Pakistan was still contending with unprecedented flooding that killed 1,739 people, destroyed more than 2 million homes, and at one point submerged as much as one third of the country.

Mohmand, of the militant organization, said a fighter carried out the attack to avenge the killing of Abdul Wali, who was widely known as Omar Khalid Khurasani, and was killed in neighboring Afghanistan’s Paktika province in August 2022.

Prime Minister Shahbaz Sharif condemned the bombing, and ordered authorities to ensure the best possible medical treatment for the victims. He also vowed “stern action” against those who were behind the attack.

Sharif traveled to Peshawar and visited the wounded at the hospital. His office said he would receive a briefing about the security situation in the northwest.

Former Prime Minister Imran Khan called the bombing a “terrorist suicide attack” in a Twitter post. “My prayers & condolences go to victims families,” said the ex-premier. “It is imperative we improve our intelligence gathering & properly equip our police forces to combat the growing threat of terrorism.”

Cash-strapped Pakistan is currently facing a severe economic crisis and is seeking a crucial installment of $1.1 billion from the International Monetary Fund — part of its $6 billion bailout package — to avoid default. Talks with the IMF on reviving the bailout have stalled in the past months.

Sharif’s government came to power last April after Imran Khan was ousted in a no-confidence vote in Parliament. Khan has since campaigned for early elections, claiming his ouster was illegal and part of a plot backed by the United States. Washington and Sharif have dismissed Khan’s claims.