Pakistani police say gunmen riding on motorcycles opened fire on a bus carrying Shi'ite Muslim pilgrims in the southwest, killing three people.

Wednesday's attack took place on the outskirts of Quetta, the capital of Baluchistan province.

Officials say at least nine people were wounded in the attack.

Elsewhere, police say at least five militants were killed and two policemen wounded in a gunfight near the city of Peshawar.

Authorities said at least 30 insurgents launched an attack Wednesday against a police checkpoint. Police say they did not suffer major casualties because they were tipped off about the raid.

In a separate incident, a bomb blast at a checkpoint in Jamrud in the Khyber tribal area killed a policeman and wounded three others.

The number of attacks by insurgents in Pakistan has markedly increased since U.S. commandos early last month raided the Pakistani hideout of al-Qaida leader Osama bin Laden and killed him.

Nearly 4,500 people have been killed throughout Pakistan in attacks blamed on the Taliban and Islamic terror networks since government troops assaulted a radical mosque in Islamabad in 2007.