Suspected Sunni extremists opened fire on Shiite Muslims travelling through south-western Pakistan today, killing 13 people and injuring seven others in the latest apparent sectarian attack to hit the country, police said.
Sunni militants with ideological and operational links to al-Qaida and the Taliban have carried out scores of bombings and shootings against minority Shiites in recent years, but the past couple weeks have been particularly bloody.
The gunmen who carried out today's attack were riding motorbikes and stopped a bus carrying mostly Shiite Muslims who were heading for work at a vegetable market on the outskirts of Quetta, the capital of Baluchistan province, said police official Hamid Shakeel.
They forced people off the bus, made them stand in a line and then opened fire, he said.
The dead included 12 Shiites and one Sunni, he said. Seven people were wounded - five Shiites and two Sunnis.
Local TV footage showed relatives wailing at the hospital where the dead and wounded were taken. One relative hugged a wounded man as another walked by, his clothes soaked with blood.
Shiites blocked the main highway on the outskirts of Quetta to protest at the killings and set fire to the bus which took the dead and wounded to the hospital.
Sunni extremists carried out a similar attack on Shiite pilgrims travelling through Baluchistan about two weeks ago, killing 26 people.
Pakistan is a majority Sunni Muslim state, with around 15% Shiite.
Most Sunnis and Shiites live together peacefully in Pakistan, though tensions have existed for decades. In the 1980s and 1990s, Pakistan became the scene of a proxy war between mostly Shiite Iran and Sunni Saudi Arabia, with both sides funnelling money to sectarian groups which regularly targeted each other.
The level of sectarian violence has declined somewhat since then, but attacks continue. In recent years, Sunni attacks on Shiites have been far more common.
The groups have been energised by al-Qaida and the Taliban, which are also Sunni and share the belief that Shiites are infidels and it is permissible to kill them.
The Sunni-Shiite schism over the true heir to Islam's Prophet Muhammad dates back to the seventh century.
Lashkar-e-Jhangvi, one of the country's most ruthless Sunni militant groups, claimed responsibility for the attack in Baluchistan two weeks ago.
One of its alleged leaders, Malik Ishaq, was released from prison on bail in July after being held for 14 years on charges, never proven, of killing Shiites.
Ishaq was re-arrested about a week ago after making inflammatory speeches against Shiites in the country.
He was not charged but detained under a public order act, which means he can be held for three months.
It is not clear whether Ishaq's speeches have been connected to the recent wave of sectarian attacks.