Zulfiqar Naqvi, a sessions judge, was attacked as he came out of his home in Quetta, the capital of Balochistan, police officials said.
They described the incident as a sectarian attack as the slain judge was a Shia.
The judge was heading to work when the gunmen, waiting outside his home at Saryab Road, fired indiscriminately.
Naqvi and the two other men were killed instantly, officials said.
The attackers, who were riding a motorcycle, fled after the shooting.
No group claimed responsibility for the attack.
Banned extremist groups like the Lashkar-e-Jhanvi are usually blamed for such attacks.
Quetta and other parts of Balochistan have witnessed a series of sectarian attacks over the past few years. Scores of people have died in these incidents.
The Balochistan Bar Association condemned the killing of Naqvi and announced lawyers would boycott court proceedings across the province.
The Tahafuz-e-Azadari Council, a leading Shia group, called for three days of mourning and appealed to the Chief Justice of Pakistan to take suo moto notice of the targeted killing.
Islamabad: Unidentified gunmen shot dead a Shi’ite judge, his bodyguard and driver in a sectarian attack in Quetta city of southwest Pakistan on Thursday, officials said.
First Published: Thursday, August 30, 2012, 12:26