The suicide attack that killed opposition leader and former Prime Minister Benazir Bhutto has sparked riots in several cities and thrown Pakistan's crucial January elections into doubt. VOA's Barry Newhouse reports on the developments from Washington with reporting from Ayaz Gul in Islamabad.

Benazir Bhutto arrives to address her last public rally in Rawalpindi, 27 Dec 2007

She said "the honor of Pakistan is our honor and for this honor we all are ready to sacrifice our lives."

A short while later Ms. Bhutto boarded her armored car, thronged by supporters. As she waved to the crowds with her torso extending out of the sunroof, witnesses said a man wearing a suicide vest walked up to the car, shot the 54-year-old opposition leader in the neck, and then detonated a blast that killed at least 20 people.

Ms. Bhutto was rushed to a nearby hospital, where doctors declared her dead Thursday evening.

President Pervez Musharraf speaks on Pakistan Television and Radio in Islamabad, 27 Dec 2007

He blamed her assassination on what he called extremists and terrorists who have been threatening Pakistan's integrity. The president vowed to eliminate terrorist forces from Pakistan.

While Ms. Bhutto had frequently expressed concerns about Islamic militants trying to assassinate her, she also said old political foes, including some government officials, could try to kill her.

A Benazir Bhutto supporter cries out aloud as he mourns her killing, as a car burns after being set afire by protesters in Lahore, 27 Dec 2007

Several casualties were reported in the riots.

While security forces tried to contain the violence and asked people to stay indoors, Ms. Bhutto's supporters began transporting her body to the family grave in Larkana in southern Sindh province.

Nawaz Sharif  leaves hospital where Benazir Bhutto died in Rawalpindi, 27 Dec 2007

The former prime minister also called on President Musharraf to step down.

Ms. Bhutto's Pakistan People's Party and Nawaz Sharif's Pakistan Muslim League Party are the country's two strongest opposition parties and their participation has been considered crucial to ensuring credible elections.