ISLAMABAD - Five people were killed and 20 others injured when a suicide bomber detonated himself inside a seminary in Pakistan's northwestern Khyber Pakhtunkhwa province on Friday, police and rescue officials said.

The incident happened at "Darul Uloom Haqqania" in Nowshera district, with the seminary's caretaker, Maulana Hamid ul Haq Haqqani, being the target of the attack, and he was critically injured in the blast, Inspector General of Police Zulfiqar Hameed told local media.

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The incident happened when a suicide bomber blew himself up among worshippers gathered to offer the Friday prayers, Abdul Rashid, the district police officer told media.

Talking to Xinhua, Bilal Faizi, the spokesperson for state-run Rescue 1122, said that they had shifted 20 injured people to the hospital and most of them are in critical condition.

Emergency has been imposed in three hospitals of the district, while hospital administrations in the provincial capital city of Peshawar have also been directed to remain on high alert.

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No group has claimed responsibility for the attack yet.

The area has been cordoned off for investigation.