ISLAMABAD, Pakistan — Gunmen opened fire on a commuter van and a rickshaw in the southwestern city of Quetta on Saturday, killing at least 11 Shiite Muslims, according to police officials. It was the latest in a series of deadly sectarian attacks in the city in the past few days.

A banned Sunni extremist militant group, Lashkar-e-Jhangvi, claimed responsibility for the attack.

Quetta, the capital of Baluchistan Province, which borders Afghanistan and Iran, has a history of sectarian and nationalist violence. Sunni extremists in the region have repeatedly attacked minority Shiites, who are mostly members of the Hazara ethnic group.

The latest spate of sectarian violence began with the killing of a Sunni scholar in Quetta on Thursday. Since then, Sunni militants have carried out several attacks on Shiites.

On Friday, gunmen attacked a bus carrying Shiite pilgrims, killing seven.

The police began rounding up members of the Sunni militant group and other suspects on Friday. On Saturday, Rao Amin Hashim, the inspector general of the provincial police, said that they had arrested 250 people and were conducting raids to detain more suspects.