KARACHI, Pakistan (Reuters) - Pakistani police arrested dozens of people in a crackdown on more than 90 seminaries in Karachi, following a series of sectarian shootings in the country’s largest city, officials said on Monday.

Provincial police chief Allah Dino Khwaja told Reuters the crackdown was aimed at both Sunni and Shi’ite seminaries.

Five supporters of the Sunni Ahle Sunnat Wal Jamaat (ASWJ), which advocates for Shi’ites to be legally declared non-Muslim and has a violent offshoot that targets Shi’ite mosques, were killed in drive-by attacks in Karachi on Friday.

On Oct. 29, five Shi’ites were shot dead at a gathering in the city’s North Nazimabad area, an attack claimed by Lashkar-e-Jhangvi al-Alami, one of ASWJ’s offshoots.

A security official, speaking on condition of anonymity, said that “dozens” had been arrested in the crackdown.

Among them were two men, members of Lashkar-e-Jhangvi, responsible for 28 targeted attacks on Shi’ites and security forces, provincial Chief Minister Murad Ali Shah told reporters.

The men were responsible for several high-profile attacks, including the killing of celebrated Sufi singer Amjad Sabri earlier this year, and the Oct. 29 attack.

Shah said that a “huge number” of weapons had been recovered after their arrests.

Over the weekend, three prominent leaders of the Shi’ite community were picked up by security forces for their alleged role in Friday’s shootings.

The arrests prompted protests by Shi’ites in the Malir area of Karachi, where demonstrators blocked a road and were forcibly cleared by police firing tear gas, rubber bullets and automatic weapons.

It was not immediately clear if there were any casualties.

Police also searched the Siddiq-e-Akbar mosque, considered the Karachi headquarters of the ASWJ, on Monday. The group’s secretary-general, Taj Hanafi, and 10 other suspects were detained, said a police official, speaking on condition of anonymity.

The ASWJ was officially banned as a terrorist organisation in 2012, but its workers continue to operate openly.

Violent crime has dropped significantly in Karachi, a teeming metropolis of more than 18 million people, since the launch of a paramilitary operation three years ago.

Shi’ite Muslims make up about 20 percent of Pakistan’s 190 million people and sectarian attacks against them have become increasingly common in recent years.

Since 2002, more than 2,500 Shi’ites have been killed in such attacks, according to data gathered by the South Asia Terrorism Portal.