Al Qaida took responsibility for assassinating Pakistani former prime minister Benazir Bhutto, Israel Radio quoted a local TV station as reporting. The Foreign Office in Islamabad said in a statement it was not certain as to the report's veracity, but suggested that those responsible were perhaps groups that carried out terrorist attacks in Pakistan in the past. Bhutto's enraged supporters burned vehicles and attacked shops across Pakistan after the charismatic former prime minister was shot and killed Thursday by an assassin as she waved to supporters from the sunroof of her armored vehicle. The attacker then blew himself up, killing 20 others. Bhutto's death sparked violence that killed at least nine people and plunged efforts to restore democracy to this nuclear armed US ally into turmoil. Another opposition politician, Nawaz Sharif, announced he was boycotting January 8 parliamentary elections, and President Pervez Musharraf debated whether to call off the poll. Musharraf blamed Islamic terrorists for the killing. "Today, after this tragic incident, I want to express my firm resolve ... we will not rest until we eliminate these terrorists and root them out," he said in a nationally televised speech. In the US, a tense looking President George W. Bush strongly condemned the attack "by murderous extremists who are trying to undermine Pakistan's democracy." White House spokesman Scott Stanzel said Bush spoke briefly by phone with Musharraf. Bhutto's death left a void at the top of her Pakistan People's Party and underscored the chaos and violence plaguing this nation, a key US ally in the fight against terrorism. Her supporters questioned why the government had not provided her better security in the wake of death threats and previous attempts on her life. As news of her death spread, supporters gathered at the hospital where she had been taken, smashed glass doors, stoned cars and chanted, "Killer, Killer, Musharraf." At least nine people were killed in the violence following her death. One man was killed in a shootout between police and protesters in Tando Allahyar, a town 190 kilometers (120 miles) north of Karachi, said Mayor Kanwar Naveed. Four others were killed in Karachi, two were killed elsewhere in the southern Sindh province and two others in Lahore, police said. In Karachi, Pakistan's commercial hub, shop owners quickly shuttered their stores as protesters set tires on fire on the roads, torched several vehicles and burned a gas station, said Fayyaz Leghri, a local police official. Gunmen shot and wounded two police officers, he said. Violence also broke out in Lahore, Multan, Peshawar and many other parts of Pakistan, where Bhutto's supporters burned banks, state-run grocery stores and private shops. Some set fire to ruling party election offices, according to Pakistani media. Authorities would deploy troops to stop violence if needed, said Akhtar Zamin, home minister for Sindh province. Musharraf convened an emergency meeting with his senior staff to discuss a response to the killing and whether to postpone the election, an official at the Interior Ministry said, speaking on condition of anonymity because of the sensitivity of the talks. Musharraf also announced three days of mourning for Bhutto, with all businesses, schools and banks in the country to be closed. The killing could strengthen the increasingly unpopular Musharraf by eliminating a strong rival, or weaken him by sparking uncontrollable riots across the country. The United States was also struggling to reformulate its plan to stabilize the country based on a rapprochement between Bhutto and Musharraf. The UN Security Council vigorously denounced the killing and urged "all Pakistanis to exercise restraint and maintain stability in the country." Hours after her death, Bhutto's body was carried out of the hospital in a plain wooden coffin by a crowd of supporters. Her body was to be sent for burial to her ancestral home near the southern city of Larkana. Sharif, another former premier and leader of a rival opposition party, demanded Musharraf resign immediately and announced his party would boycott the elections, seen as vital to restoring democracy after eight years of authoritarian rule under Musharraf. He also called for the resignation of Musharraf, a former army chief who toppled Sharif in a 1999 coup. "Musharraf is the cause of all the problems. The federation of Pakistan cannot remain intact in the presence of President Musharraf," he said. Next to Musharraf, Bhutto, 54, was the best known political figure in the country, serving two terms as prime minister between 1988 and 1996. She was respected in the West for her liberal outlook and determination to combat the spread of Islamic extremism, a theme she returned to often in her campaign speeches in recent days. Addressing more than 5,000 supporters in the garrison city of Rawalpindi on Thursday, Bhutto scoffed at reports that foreign troops would be sent here to help fight resurgent militants linked to the Taliban and al Qaida in the area bordering Afghanistan. "Why should foreign troops come in? We can take care of this, I can take care of this, you can take care of this," she said. Minutes later, as Bhutto left the rally in a white sports utility vehicle, the attacker struck. On the road outside, youths chanted her name and supportive slogans, Sardar Qamar Hayyat, an official from Bhutto's party who was about 10 yards (meters) away. A smiling Bhutto stuck her head out of the sunroof and responded, he said. "Then I saw a thin, young man jumping toward her vehicle from the back and opening fire. Moments later, I saw her speeding vehicle going away. That was the time when I heard a blast and fell down," Hayyat said. Bhutto was rushed into emergency surgery. A doctor on the surgical team said a bullet in the back of her neck damaged her spinal cord before exiting from the side of her head. Another bullet pierced the back of her shoulder and came out through her chest, he said on condition of anonymity because he was not authorized to speak to the media. She was given an open heart massage, but the spinal cord damage was too great, he said. "At 6:16 p.m. she expired," said Wasif Ali Khan, a member of Bhutto's party who was at Rawalpindi General Hospital. Makhdoom Amin Fahim, chairman of Bhutto's party, called for a thorough investigation. "The Bhutto family and the party should know who is behind the attack," he said. Bhutto had returned to Pakistan from an eight-year exile on Oct. 18, and her homecoming parade in Karachi was also targeted by a suicide attacker, who killed more than 140 people. She narrowly escaped injury in that attack. On Thursday, hundreds of riot police manned security checkpoints at the park for Bhutto's first public meeting in the city since her return. In November, Musharraf forced her to cancel a planned rally here, citing security fears. In recent weeks, suicide bombers have repeatedly targeted security forces in Rawalpindi, a city near the capital where Musharraf stays and the Pakistan army has its headquarters. Bhutto was killed just a few kilometers (miles) from the scene of her father's violent death 28 years earlier. Zulfikar Ali Bhutto, a former prime minister and the founder of the party that his daughter would later lead, was executed by hanging in 1979 in Rawalpindi on charges of conspiracy to murder that supporters said was politically motivated by the then-military regime. His killing led to violent protests across the country similar to the ones that raged across the country Thursday. Afghan President Hamid Karzai, who met with Bhutto just hours before her death, called her a brave woman with a clear vision "for her own country, for Afghanistan and for the region - a vision of democracy and prosperity and peace."