PESHAWAR, Pakistan (AP) — A suicide bomber struck Monday inside a mosque within a police compound in the northwestern Pakistani city of Peshawar, killing at least 28 people and wounding as many as 150 worshippers, most of them police officers, officials said.

The bombing drew nationwide condemnation from opposition political parties and government officials. Ghulam Ali, the provincial governor in Khyber Pakhtunkhwa, where Peshawar is the capital, said there were fears the death toll could rise even further.

Most of the casualties were police officers — the targeted mosque is located within a sprawling compound, which also serves as the city’s police headquarters. Police said between 300 to 350 worshippers were inside the mosque when the bomber detonated his explosives.

No one immediately claimed responsibility for the bombing, said Saddique Khan, a senior police official in Peshawar, but the Pakistani Taliban have been blamed in similar suicide attacks in the past.

The police compound is located in a high-security zone in Peshawar, along with several government buildings, and it was unclear how the bomber managed to penetrate so deep inside the zone unnoticed.

The impact of the explosion collapsed the roof of the mosque, which caved in and injured many, according to Zafar Khan, a local police officer.

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

Rescuers scrambled trying to remove mounds of debris from the mosque grounds and get to worshippers still trapped under the rubble, police said. At a nearby hospital, many of the wounded were listed in critical condition as the casualty toll rose.

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

Former Prime Minister Imran Khan also condemned the bombing, calling it a “terrorist suicide attack” in a Twitter posting. “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.”

Peshawar has been the scene of frequent militant attacks. The Pakistani Taliban, are known as Tehreek-e-Taliban Pakistan or TTP, and are separate group but also a close ally of the Afghan Taliban, who seized power in neighboring Afghanistan in August 2021 as US and NATO troops were in the final stages of their pullout from the country after 20 years of war.