A suicide attacker exploded a bomb among police on guard near a Shiite Muslim mosque in this northwestern Pakistani city late Saturday, killing at least 15 people, including the city police chief, and wounding more than 30, officials said.

Paramilitary forces in armored vehicles were deployed to patrol Peshawar after the attack that came as Pakistan's minority Shiites started to commemorate their most important religious festival of Ashoura, often a target for sectarian violence.

Analysts say the alarming Sunni-Shiite fighting that has brought chaos to Iraq risks igniting tensions between the sects in other Muslim countries such as Pakistan.

President Gen. Pervez Musharraf, a key U.S. ally in fighting Al Qaeda, condemned the "terrorist attack" and ordered an immediate inquiry, the state-run Associated Press of Pakistan reported.

The blast went off on a street corner in the crowded Qissakhwani Bazaar in an old quarter of Peshawar, the main city in northwestern Pakistan, about 656 feet from the Imam Barga Najmul Hassan mosque from where Shiites had been preparing to start a procession.

It caused chaos and a power outage that left the area in darkness, complicating rescue efforts. Police and ambulance workers used vehicle headlights to illuminate the bomb scene, and could be seen retrieving wounded people, corpses and body parts.

Other officers restrained angry Shiites who gathered nearby, chanting religious slogans.

Police official Aziz Khan said 15 people were killed in the blast and more than 30 were wounded. Most of the victims were police and municipal officials who were clearing the route for the Shiite procession.

Provincial police chief Sharif Virk said city police chief Malik Saab was among the dead.

At the bomb site, investigators found what appeared to be two detached legs from a suicide attacker, police officer Raza Khan said. Remnants of a suicide belt with pieces of metal and a grenade were also found, said a senior police officer who requested anonymity because he was not authorized to talk about the investigation.

Aziz Khan had been on duty near the mosque when the bomb went off.

"I was shocked by a big explosion. I thought my eardrums had burst. Then there were flames and the people were in panic. I remembered that there was a police contingent, so I went to see what had happened to my colleagues. Many were wounded in a bad way," he said.

The dead and wounded were brought to Peshawar's Lady Reading hospital, where hundreds of people crowded seeking news on loved ones. By loudspeaker, hospital officials appealed for calm and blood donations.

There was no immediate claim of responsibility, but suspicion will likely fall on Sunni extremists.

This weekend marks the start of the festival of Ashoura, when Shiites mourn the 7th century death of the prophet Muhammad's grandson, Imam Hussein. Commemorations are planned over the next few days, culminating in processions on Monday and Tuesday by devotees who flail their backs with blades and chains.

Pakistan has a history of sectarian violence.

Shiites represent about 20 percent of Pakistan's Muslims, and Sunnis about 80 percent. Most Shiites and Sunnis co-exist peacefully, but militant groups on both sides are blamed for sectarian attacks that claim scores of lives every year.

Talat Masood, a political and defense analyst, said Shiite processions have been targeted in the country in recent years. But he said the sectarian violence in Iraq could galvanize sectarian militant groups in Pakistan, fueling further unrest.

"The increasing sectarian violence in Iraq will definitely add tension here, and I think it is going to reunite sectarian elements, who have targeted each others worship places in the past," he said.

The Sunni-Shiite schism over who was the true heir to Islam's Prophet Muhammad dates back to the seventh century.

The attack happened as a U.S. congressional delegation visited Islamabad, about 90 miles from Peshawar, and met President Musharraf. Talks were expected to touch on cooperation against Taliban and Al Qaeda militants and U.S. aid to the South Asian country, officials said.