Many of the protesters in Quetta, the capital of Baluchistan, dispersed peacefully. But relatives of the bombing victims who had refused to bury their loved ones in protest said they would continue their demonstration until a key militant leader was arrested. Shiite protesters in other Pakistani cities said they would also continue their protests until the demand was met.

Leaders of the protest had earlier demanded the army take control of Quetta and launch a targeted operation against Lashkar-e-Jhangvi, the group that claimed responsibility for Saturday's bombing in a produce market. Shiites have criticized police and paramilitary forces under control of the Interior Ministry in Quetta for failing to protect the minority sect, which comprises up to 20 percent of the country's population of 180 million.

There was no indication the army would take control of the city. But the government announced that paramilitary forces began an operation against Lashkar-e-Jhangvi and other militant groups Monday night.

The government also replaced the top police officer in Baluchistan on Tuesday, said Fayaz Sumbal, deputy police chief in Quetta. Sumbal has also been ordered to replace the chief of police operations in Quetta, he said.

"Our demands have been accepted," a top Shiite leader in Quetta, Amin Shaheedi, told reporters after holding talks with a government delegation sent from Islamabad. "We appeal to our people to go to their homes in a peaceful manner."

But another Shiite leader, Rahim Jaffery, said the relatives of the bombing victims would not bury their loved ones until authorities arrest a key suspect in a double bombing in January at a billiards hall in Quetta that also targeted Shiites and killed 86 people. The suspect is Ramzan Mangal, a senior leader of the Sunni extremist group Ahle Sunnat Waljamaat, he said.

Radical Sunni militants have stepped up attacks against Shiites over the past year because they do not consider them to be real Muslims. Violence has been especially bad in Baluchistan province, which has the highest concentration of Shiites in the country.

It remains to be seen what impact the government's recent actions will have on the problem of sectarian violence in Quetta. Suspected militants are notoriously difficult to prosecute in Pakistan, and it's unclear if the operation against Lashkar-e-Jhangvi and others will be sustained.

Pakistan has launched numerous military operations against militants in recent years, but the focus has been on the Pakistani Taliban, who have been waging a bloody insurgency against the state that has killed thousands of people.

Rights organizations have criticized the government for not doing enough to target militant groups attacking Shiites. They explain this apathy by pointing to past connections between the country's military and anti-Shiite militants, and also allege the sectarian groups are seen as less of a threat than the Taliban because they are not targeting the state. Political parties have also relied on banned sectarian groups to deliver votes in elections.

The four Lashkar-e-Jhangvi militants killed Tuesday in a suburb of Quetta included Shah Wali, a senior commander involved in attacking Shiites and police officials, said Durrani, the home secretary. Others included Abdul Wahab, a key planner and recruiter; Naeem Khan, a logistics expert who provided explosives; and Anwar Khan, a rank and file militant, said Durrani.

Seven other Lashkar-e-Jhangvi militants were arrested in the operation Tuesday, said Durrani. The more than 170 suspected militants arrested earlier included Haji Mohammed Rafiq, a prominent member of Ahle Sunnat Waljamaat, said the home secretary.

Pakistani Prime Minister Raja Pervaiz Ashraf first announced the operation in a statement issued by his office Tuesday that said it "aimed at eliminating those responsible for playing with lives of innocent civilians and restoring peace and security in Quetta."

Last year was the bloodiest in history for Pakistan's Shiites, according to Human Rights Watch. Over 400 were killed in targeted attacks across the country, at least 125 of whom were died in Baluchistan.

With two massive bombings targeting Shiites in as many months this year already, 2013 looks like it could be even worse.

The government promised to take action against sectarian militants following protests in January against the billiards hall bombing. Shiites brought the bodies of the victims into the street at the time and refused to bury them unless the government took steps to protect them.

After four days, Islamabad decided to dissolve the provincial government and put a federally-appointed governor in charge. The government said paramilitary forces would receive police powers and launch an operation against the militants behind the billiards hall attack. But officials refused to put the army in control of the city, as they have done this time around.

Around 15,000 Shiites took to the streets to protest near the site of the recent attack Tuesday, before their leaders called an end to the demonstration. Others stayed beside the bodies of the bombing victims inside a nearby mosque. Some chanted "God is great." Others held placards that said "Stop killing Shiites."

Shiite leaders made speeches to the crowd saying their demands had been accepted and urged them to disperse peacefully after the talks with the government delegation. They also urged Shiites in other parts of the country, such as Karachi and Islamabad, to end smaller protests held over the past few days.

Associated Press writers Munir Ahmed, Zarar Khan, Asif Shahzad and Sebastian Abbot contributed to this report from Islamabad.