At least four policemen including SP Mubarak Shah were gunned down in Quetta on Thursday by unidentified armed men.
Police sources said the firing incident took place in the Kali Deeba area of the city.
Frontier Corps and police reached the incident site and cordoned the area. A search operation has been initiated to arrest the culprits behind the attack.
Prime Minister Nawaz Sharif expressed his grief over the incident.
Meanwhile, Balochistan Chief Minister Sanaullah Zehri took notice of the killings and directed the law enforcers to arrest the killers behind attacks on the policemen.
The killing comes two days after Chaman DPO SSP Sajid Khan Mohmand was martyred in a suicide attack at Eidgah Chowk area of the district.
At least 10 people were also injured when a bike-riding suicide bomber targeted the convoy of the senior police officer.
Mineral-rich Balochistan has been plagued for decades by a separatist insurgency and sectarian killings. Taliban and other extremist militants also operate in the province, which shares borders with Afghanistan and Iran.