Police in Pakistan say a bomb has exploded at a bus station in the country's northwest, killing at least three people.

Senior police officer Ishtiaq Marwat says Saturday's attack in the northwestern town of Kohat also wounded four people.

He said the bomb struck a moving bus when hundreds of passengers were gathered there to leave for different cities to celebrate the Muslim festival of Eid al-Adha. Footage from Pakistani news channels showed a damaged bus.

No one claimed responsibility for the attack, though Kohat has been the scene of sectarian attacks in recent years, most blamed on Pakistani Sunni Muslim militants.

Kohat is located about 50 kilometers (30 miles) southwest of Peshawar, the capital of Khyber-Pakhtunkhwa province.