Islamabad, Pakistan (CNN) -- A suicide bomber killed at least 23 people Friday in the center of a northern Pakistan city, police and hospital officials said.
The man detonated his explosives near a marketplace in Hangu in the volatile Khyber Pakhtunkhwa province, which borders Afghanistan and has long been a haven for militants, including Pakistani Taliban.
He may have been targeting worshippers who were leaving midday prayer services in area where both a Sunni and a Shia mosque are located, said police spokesman Imtiaz Shah. There has been no claim of responsibility.
The attack injured 56 people, 16 critically, said hospital spokesman Dr. Nawab Hussein.
It came two days after gunmen killed seven people in Pakistan's southwestern Balochistan province, and a bomb blast ripped through Karachi and left two dead.
This month, 97 people have died in bombings in Balochistan, leading to protests among Shiites who complain that the government has done too little to protect them.