QUETTA, Pakistan (AP) — The death toll from a horrific bombing that tore through a crowded vegetable market in a mostly Shiite Muslim neighborhood of southwestern Pakistan climbed to 81 with many of the severely wounded dying overnight, a Pakistani police official said Sunday.

Police official Fayyaz Saumbal said 164 people also were wounded by the explosion Saturday in the city of Quetta just as people shopped for produce for their evening meal. The bomb was hidden in a water tank and towed into the market by a tractor, Quetta police chief Zubair Mahmood told reporters.

It was the deadliest incident since bombings targeting Shiites in the same city killed 86 people earlier this year, leading to days of protests that eventually toppled the local government.

Shiites have been increasingly attacked by militant groups who view them as heretics and non-Muslims in the country, which is dominated by Sunni Muslims. Many of the Shiites in Quetta, including those in the neighborhood attacked Saturday, are Hazaras, an ethnic group that migrated to Pakistan from Afghanistan more than a century ago.

The remote-controlled bomb destroyed shops, caused a two-story building to collapse and left a massive crater where it exploded.

Local residents rushed the victims to three different area hospitals, often in private vehicles because there weren't enough ambulances to transport them.

Angry members of the minority Shiite sect protested in the streets, blocking roads with burning tires and throwing stones at passing vehicles. Some fired into the air in an attempt to keep people away from the area in case of a second explosion. Sometimes insurgents stagger the explosions as a way to target people who rush to the scene to help those killed or wounded in the first, thus increasing the death toll.

On Sunday morning, the city was completely shut down as people observed strike called by the Hazara Democratic Party as a way to honor the dead and protest the repeated slaughter of members of their ethnic and religious community.

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Bostan Ali, the Quetta chief of the Hazara Democratic Party, said the group is planning another protest in the city similar to one held in January after twin bombings in Quetta killed at least 86 people. During that protest, Hazaras refused to bury their dead for four days, instead protesting in the streets alongside coffins holding their loved ones.

"We will not bury our dead until stringent action is taken against terrorists who are targeting and killing Shiites," Ali said.

The rally in January sparked similar events across the country and an outpouring of sympathy for Shiites. The prime minister flew to Quetta and after meeting with protesters dismissed the local government.

But Saturday's massive blast indicated that the militant groups are still capable of targeting Shiites.

The police chief said investigators were not certain who was behind the bombing but a local television station reported that Lashkar-e-Jhangvi, a Sunni extremist group that has targeted Shiites in the past, had called to claim responsibility.

Most of the Shiites in the area are Hazaras, and they were quick to blame Lashkar-e-Jhangvi.

"This evil force is operating with the patronage of certain elements in the province," said Qayum Changezi, the chairman of a local Hazara organization.

Quetta is the capital of Baluchistan province, the country's largest but also the one with the smallest population.

The province is facing challenges on many fronts. Baluch nationalist groups are fighting an insurgency there to try to gain a greater share of income from the province's gas and mineral resources. Islamic militants, like the sectarian group Lashkar-e-Jhangvi, are also active in the province. And members of the Afghan Taliban are believed to be hiding in the region.

Lashkar-e-Jhangvi took its name after a firebrand Sunni cleric who gave virulently anti-Shiite sermons.

Pakistan's intelligence agencies helped nurture Sunni militant groups like Lashkar-e-Jhangvi in the 1980s and 1990s to counter a perceived threat from neighboring Iran, which is mostly Shiite. Pakistan banned Lashkar-e-Jhangvi in 2001, but the group continues to operate fairly freely.

Last year was particularly deadly for Shiites in Pakistan. According to Human Rights Watch, more than 400 were killed in targeted attacks across the country. The human rights group said more than 125 were killed in Baluchistan province, most of whom belonged to the Hazara community.

Rights groups have accused the government of not doing enough to protect Shiites in the country.