Iran Press/ Asia: The bombing happened while a cleric was delivering a lecture about the teachings of Islam at the main hall of the Jamia Zubairia madrassa, said police officer Waqar Azim.
He said initial investigations suggest the bomb went off minutes after someone left a bag at the madrassa.
Mohammad Ali Gandapur, another senior police official, confirmed the blast and details. He said two teachers were among the wounded.
Several of the wounded were in critical condition, and hospital authorities feared the death toll could climb further.
No group claimed immediate responsibility for the attack.
Peshawar is the provincial capital of Pakistan's Khyber Pakhtunkhwa province bordering Afghanistan.
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