Unidentified gunmen in Pakistan have killed at least six Shiite Muslims and injured several others in an attack on a bus in the southern port city of Karachi.
Pakistani police say the bus was carrying worshipers to Friday prayers, when it came under attack from at least two masked gunmen on a motorcycle.
According to eye-witnesses, the attackers intercepted the vehicle on a deserted road on the outskirts of Karachi and first opened fire on the driver, killing him instantly. The gunmen then sprayed bullets with automatic weapons into the vehicle from all sides and fled the scene.
Most of the victims are employees of a state-run space research organization in the city. An off-duty Pakistani soldier traveling on the bus is also among the dead.
Several of those wounded in the attack are said to be in serious condition.
No group has taken responsibility, but some police officials say it could be the work of extremists from the majority Sunni Muslim community. Authorities have launched an investigation into what appears to be targeted killings, but no arrests have been made so far.
Minority Shiite leaders have condemned Friday's shooting, and are demanding better security for members of their community.
Hundreds of people have died in the sectarian violence in Pakistan in recent years. In one of the worst such attacks in July, more than 50 Shiite worshipers were killed, when suicide attackers stormed a mosque in the southwestern city of Quetta.
The Pakistani government has outlawed several Sunni and Shiite militant groups, but there is no let-up in the violence.