Gunmen on Thursday shot dead four Pakistani Shiite Muslims and two UN employees in Baluchistan, a region plagued by Taliban violence and a separatist insurgency, police said.
Gunmen on a motorbike fired at a van carrying members of the minority Muslim community in the Speeni Road neighbourhood of Quetta city, the capital of the southwestern province, police official Jamil Kakar told AFP.
"Four people, including a woman, were killed and seven others were wounded," Kakar said, adding that it appeared to be a "sectarian" attack.
Dozens of Shiites demonstrated in Quetta's main Meezan Chowk square and outside the provincial police chief's office, and torched a motorcycle at a local hospital to protest against the killings, witnesses said.
Human rights groups have heavily criticised Pakistan for failing to crack down on sectarian violence between the majority Sunni Muslim community and Shiites, who account for around 20 percent of the population.
Thousands of people have died in related unrest since the late 1980s.
In a separate incident, gunmen shot dead two local employees of the UN Food and Agriculture Organisation in Mastung, a city 40 kilometres (25 miles) south of Quetta, police official Shakir Ullah told AFP.
"A driver and a staff member of FAO were killed and another staffer wounded after gunmen fired at their vehicle," Ullah said.
It was not immediately clear why they were targeted and so far no one has claimed responsibility, he said.
Human rights groups say hundreds have been detained, killed or gone missing as government troops have tried to crush a Baluch uprising that began in 2004.
Baluch rebels want a greater share of the oil, gas and mineral deposits in the region, which borders Iran and Afghanistan. Taliban and sectarian extremists have also taken up arms in the region.