Hundreds of youths set fire to a Pizza Hut restaurant, two gas stations and a dozen vehicles in Pakistan's biggest city, Karachi, after Saturday's funeral for an Islamic Shiite cleric killed in a suicide attack.

Rioters rampaged through a busy commercial area a day after a suicide bomber killed cleric Allama Hassan Turabi, his cousin and a police guard.

Police fired shots in the air, swung batons and used tear gas to control the crowd.

Hours earlier, Turabi was buried at a city cemetery after more than 8,000 people, beating their chests with their hands as a sign of grief, packed the city streets for his funeral.

Most of the crowd dispersed peacefully after the ceremony, but a gang of youths damaged shops and torched a Pizza Hut, two state-owned gas stations and several vehicles, apparently expressing general anger at the U.S. and Pakistani governments.

Turabi's son denounced the violence.

"My father always advocated for peace and sectarian harmony, and those people who torched cars and shops have no links to my father's party," Murtaza Turabi told reporters after the funeral.

He said his father's assassination was a "conspiracy to pitch Shiites and Sunnis against each other," and he demanded punishment for those behind the suicide attack.

Pakistan is a key U.S. ally in what Washington calls the war on terror. Many Shiites identify Pizza Hut with the American administration and have burned the chain's outlets after previous attacks on their leaders.

Pakistan has been plagued for years by attacks blamed on extremist elements among the Sunni and Shiite sects of Islam, targeting places of worship and religious leaders. The attacks often lead to rioting.

About 80 percent of Pakistan's 150 million people are Sunni; most of the rest are Shiite. The majority live together in peace.

The weekend violence came despite top Shiite clerics' appeals for calm.

Senior police official Mushtaq Shah said hundreds of police had fanned out across Karachi after riots that started Friday night, when youths smashed a bank and some shops, and began arson attacks.

"We are avoiding the use of force, and trying to control situation with help from Shiite clerics," he said.

Karachi is about 750 miles northeast of Pakistan's capital, Islamabad.

Turabi, who had narrowly escaped an attempt on his life in April, had led a Shiite party called Islamic Tehreek Pakistan and was a provincial chief for the hard-line opposition Islamic coalition Mutahida Majlis-e-Amal, also called MMA, or United Action Forum.

Hours before Turabi's funeral, deputy MMA chief Allama Sajid Naqvi had said that since the slain cleric "always worked for peace and sectarian harmony," those who love him must remain peaceful.

The government has described Turabi's assassination as an act of terrorism, and promised to do all they could to arrest those behind it.

Police said they have found the suspected bomber's detached head.

A suicide bombing at a Sunni gathering in a Karachi park killed 57 people in April. It was one of Pakistan's deadliest bombings in recent years, and sparked three days of rioting in Karachi by Sunnis.