At least eight people have been killed and six injured as violence broke out in the northwestern Pakistani city of Hangu.
Police say riots erupted after gunmen opened fire in a market killing three Shiite Muslims and critically wounding another person.
The shooting happened a day after the execution of a Sunni extremist for the 1990 murder of an Iranian diplomat.
The assailants emerged from a van and sprayed bullets at a crowded market before escaping.
The incident triggered violent demonstrations in the city and exchanges of gunfire between Shiites and Sunnis.
Police say clashes between rival armed groups left five people dead and another five wounded.
(05:55:57 AEST)