The explosive device was planted underneath a donkey cart on the outskirts of Quetta, the capital of the oil-and-gas-rich Baluchistan province, which borders Iran and Afghanistan.
"The bomb targeting a police van exploded seconds after it passed by the cart, killing three passers-by and wounding six others including a policeman," local police official Sikandar Tareen told AFP.
Another local police official, Saleem Shawani, confirmed the incident and casualties.
There was no claim of responsibility, but Baluchistan suffers from Islamist militancy, sectarian violence between Sunni and Shiite Muslims and a separatist insurgency.
Gunmen riding a motorcycle shot dead the chief warden of the district prison on May 19.
Al-Qaeda-linked militant group Lashkar-e-Jhangvi claimed responsibility and said "the slain warden was a cruel person and used to subject our imprisoned leaders and workers to torture".
Hundreds of civilians have been killed since Baluch rebels rose up in 2004 against the federal Pakistani government, demanding political autonomy and a greater share of profits from the resources in the region. (*)
Editor: Kunto Wibisono
Copyright © ANTARA 2012