Gunmen opened fire on a vehicle in Pakistan's southwestern Baluchistan province on Saturday, killing 11 Shi'ite Muslims and wounding three in a suspected sectarian attack.

A woman was also among the dead in the attack in Quetta, the provincial capital of Baluchistan, where pro-Taliban Sunni militants and Baluch separatists are blamed for years of violence in the province that shares border with Iran and Afghanistan.

"The vehicle was passing by a bus stand when gunmen riding in another car opened fire, killing at least 11 people and wounding three," city's police chief Hamid Shakeel told Reuters.

Another police official said it appeared to be a sectarian attack as all those killed were Shi'ite Muslims.

The majority of Pakistanis are Sunni Muslims, with Shi'ites accounting for around 15 percent of a population of more than 170 million.

Both communities largely live in peace with each other but militants from the two sides have killed thousands of people in tit-for-tat attacks since the beginning of Islamist militancy in the country in the 1980s.

Saturday's attack came a day after eight people were killed and about 25 wounded in two separate bomb and gun attacks in two districts of Baluchistan.

Baluch nationalists have waged a low-scale insurgency for decades but Taliban militants with links to al Qaeda have also been active in Baluchistan, the largest but poorest of Pakistan's four provinces, and home to the country's largest gas and oil reserves.

Pakistan has seen a surge in violence since al Qaeda chief Osama bin Laden was killed by U.S. special forces in a secret raid in Pakistan in May.

Militants have vowed revenge for bin Laden's death.