QUETTA, Pakistan: Gunmen shot dead four Shiite Muslims on Tuesday, in a fresh sectarian attack in Pakistan's troubled southwestern province of Baluchistan, police said.

All those killed ran junk and scrap shops in Kabari Market in Quetta, the provincial capital where sectarian and separatist violence is common.

"It was a sectarian attack. Gunmen on motorbikes opened fire on them and drove away," Asif Ghafoor, a senior police official, told AFP.

The province, which borders Afghanistan and Iran, is plagued by sectarian violence between the minority Shiite and majority Sunni community, as well as by Taliban attacks and a separatist insurgency.

Riasat Ali, another police official confirmed the incident and told AFP that the victims were critically injured and died on their way to hospital.

Sectarian violence involving Sunni and Shiites, who account for around 20 percent of the population, has killed thousands of people since the late 1990s.

Despite having large reserves of oil and gas, Baluchistan remains one of Pakistan's most impoverished provinces, and bomb blasts and attacks on police and security forces are common.

In 2004 Baluch rebels rose up, demanding political autonomy and a greater share of profits from the region's mineral resources.