Police also registered a complaint by relatives of the slain Shi’ites against seven local members of an outlawed Sunni militant group whom they blamed them for the attack.
A senior police official, who asked not to be named, told Reuters 30 people had been arrested so far in an extensive investigation into the massacre on Tuesday, when Shi’ites were observing Ashura, one of the holiest days in their calendar.
The attack on the Shi’ite procession was the worst sectarian violence in Pakistan since a July suicide attack on a Shi’ite mosque in Quetta, which killed more than 57 people.
Tuesday’s attack coincided with bomb blasts that killed at least 170 people in Iraq’s holy Shi’ite city of Kerbala and the capital Baghdad.
US officials linked them to Al Qaeda, but Pakistani officials say they do not have any evidence suggesting the attacks in Pakistan and Iraq were in any way connected.
Relatives of the Pakistani victims named seven members of the outlawed Sipah-e-Sahabah group as being involved, although police said it was too early to pin the blame on any single group.
Over the weekend police released sketches of two suspects and offered one million rupees ($17,400) to anyone providing information that may lead to their capture.
Prime Minister Zafarullah Khan Jamali told a news conference on Saturday the government would conduct a “very deep” investigation into the attack.
The attackers used automatic weapons and five grenades on a crowd of thousands of Shi’ites, who make up some 15 percent of the overwhelmingly Sunni Muslim nation of 150 million people.
Residents said army and paramilitary forces were helping the police to patrol the city, still under a curfew imposed on Tuesday to prevent rioting by Shi’ites.
Enraged Shi’ites in the city of 400,000 people rampaged through Quetta after the attack, burning more than 100 shops and several homes. Residents say Sunni Muslim shop owners are furious about the vandalism.
Shi’ite leaders suspect the Quetta attack was the work of Lashkar-e-Jhangvi, an outlawed Sunni group with links to Al Qaeda that has carried out many sectarian attacks before. Witnesses said the attackers’ guns were painted with the group’s name.
