Three Shias were gunned down on Monday in Quetta, a police official said.
According to police officer Zakir Ali all three of them were killed in a sectarian drive-by shooting.
Balochistan is a flashpoint for sectarian violence involving majority Sunnis and minority Shias that has left thousands dead since the 1980s.
Earlier late Sunday, gunmen shot dead five people in attacks on two buses in Bolan as rebels staged a strike to mark the death anniversary of tribal chieftain Nawab Akbar Bugti, officials said.
According to police official Iftikhar Bugti, five people including two women were killed in the incident.
There was a “complete strike” in Quetta and several other districts on Sunday, local police chief Wazir Khan told AFP, with shops and markets closed and traffic brought to a standstill.
The halt was called by Balochistan Republican Party (BRP) leader Brahmdagh Bugti to mark the sixth anniversary of the death of his grandfather Akbar Bugti, who was killed in his mountain hideout during a military operation in 2006.
BRP spokesman Sarbaz Baloch claimed responsibility for the shooting.
“We had launched an appeal for a complete strike and the buses bound for southern Sindh and central Punjab provinces had ignored our appeal. We therefore opened fire on them,” he said in a telephone call to AFP.
Police and residents said Sunday’s strike was almost complete across the impoverished and insurgency-hit province, with 21 out of 30 districts affected.
People blocked roads and erected barricades in several places on highways leading to Iran, Karachi and other important cities, they said.
The strike was endorsed by other political and religious parties in the province, with around 300 people demonstrating in Quetta to demand the extradition and trial of former military ruler Pervez Musharraf for ordering the operation in 2006.
Baloch rebels rose up in 2004, demanding political autonomy and a greater share of profits from the oil, gas and mineral resources in the region, one of the most deprived in Pakistan.
Bomb blasts and attacks on police and security forces are frequent in the province.