A mob angered by an Al Qaeda-linked bombing in a Shiite mosque set a KFC restaurant afire in overnight rioting, killing six employees and bringing the day's overall death toll to 11, police said Tuesday.

Security in Karachi shifted into "high alert," said Rauf Siddiqi, home minister of Sindh province (search), of which Karachi is the capital.

"These incidents are happening one after the other. We are trying to find a link between them," he told the private Geo television station. "This is a criminal and merciless attack."

The bomber slipped into the mosque during a shootout with police that left another attacker and two officers dead, and blew himself up during evening prayers Monday, killing one worshipper and wounding 20.

An enraged crowd of about 1,000 Shiites, many beating their chests in mourning, rampaged afterward in this southern city, setting fire to cars and shops and killing at least six more people.

Police recovered the bodies from a KFC restaurant burned by the mob. All were restaurant employees, senior police official Manzoor Mughal said. Four were burned to death, while two others died after taking refuge in a refrigeration unit, he said.

Two electricity transformers also were burned, plunging the neighborhood into darkness.

The bombing occurred at the Madinatul Ilm Imambargah mosque in eastern Karachi, police official Asif Ijaz said. Three attackers stole an automatic weapon from a police guard outside the mosque and shot him to death, Ijaz said.

Other policemen opened fire, killing one attacker and wounding another, he said.

The third attacker managed to get inside the mosque and detonate a bomb strapped to his body, Ijaz said. Besides the one dead worshipper, four were seriously wounded, while 16 others were treated for lesser wounds, said Zafar Hussain, a mosque administrator.

"It appeared to be a low-intensity bomb because it did not cause major damage," said Mushtaq Shah, chief of police operations in Karachi.

One of the three men involved in the mosque attack was hospitalized with injuries, police said.

He gave his name as Mohammed Jamil and said he was from the outlawed Jaish-e-Mohammed (search) militant group, which is accused of orchestrating several attacks against minority Christians, Shiites and government officials, police said.

The group is mainly fighting Indian forces in India's part of Kashmir (search), but its supporters also are known for their links with Al Qaeda (search). Some are believed to have trained in Al Qaeda-run camps in Afghanistan.

The attack came three days after a suspected bomber attacked a Shiite religious gathering during a festival at a shrine near Islamabad, Pakistan's capital, killing about 20 people and injuring dozens.

Political and sectarian violence between radical groups within the majority Sunni and minority Shiite Muslims is common in Karachi.