A suicide bomber struck Monday inside a mosque within a police compound in the northwestern Pakistani city of Peshawar, killing at least 44 people and wounding over 150  others, most of them policemen, 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 policemen and 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 worshipers were inside the mosque when the bomber detonated his explosives. Sarbakaf Mohmand, a commander for the Pakistani Taliban, claimed responsibility for the attack on Twitter. 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.