Unidentified gunmen have shot and killed three Pakistani police officers in the country's southwestern province of Baluchistan.

A senior police official says Sunday's attack occurred while the officers were patrolling on the outskirts the provincial capital, Quetta.

There was no claim of responsibility for the shooting.

Baluchistan province has endured a local insurgency, Islamist militancy, and sectarian violence between majority Sunnis and minority Shi'ite Muslims.