The gunmen who attacked Tuesday were riding on motorbikes and stopped a bus carrying mostly Shia Muslims who were headed to work at a vegetable market on the outskirts of Quetta, said police official Hamid Shakeel.
The attackers forced the people off the bus, made them stand in a line and then opened fire, said Shakeel.
The dead included 11 Shias and one Sunni, he said. The wounded included four Shias and two Sunnis.
Local TV footage showed relatives wailing at the hospital where the dead and wounded were brought. One relative hugged a wounded man as another walked by, his clothes soaked with blood.
Angry men blocked the main highway on the outskirts of Quetta to protest the killings and set fire to the bus that took the dead and wounded to the hospital.
