A bomb blast near a bus killed at least six people and injured dozens in the restive Balochistan province of southwest Pakistan on Monday, officials said.

The bomb, hidden in a motorcycle, was detonated by remote control as the bus was passing through Mastung district, 50 km south of the provincial capital of Quetta.

Officials confirmed the death of six people. Over two dozen people were injured. The condition of three of the wounded was critical, officials said.

The injured were taken to a nearby hospital and those in a critical condition were later shifted to Quetta.

Nearly 50 people, including women and children, were in the bus. Footage on television showed that the bus was extensively damaged by the blast.

Police said that the intended target of the bombing might have been a bus with Shia pilgrims that passed the area minutes before the explosion.

No group claimed responsibility for the attack. Balochistan has witnessed a string of sectarian attacks that targeted the minority Shia community. Scores have died in these attacks.