http://www.nytimes.com/2007/12/28/world/asia/28pakistan.html?_r=2&hp&oref=slogin&oref=slogin

RAWALPINDI, Pakistan – Benazir Bhutto, the Pakistani opposition leader and twice-serving prime minister, was assassinated Thursday evening as she left a political rally here, a scene of fiery carnage that plunged Pakistan deeper into political turmoil and ignited widespread violence by her enraged supporters.

Ms. Bhutto, 54, was shot in the neck or head, according to differing accounts, as she stood in the open sunroof of a car and waved to crowds. Seconds later a suicide attacker detonated his bomb, damaging one of the cars in her motorcade, killing more than 20 people and wounding 50, the Interior Ministry said.

News of her death sent angry protesters swarming the emergency ward of the nearby hospital, where doctors declared Ms. Bhutto dead at 6:16 p.m. Supporters later jostled to carry her bare wooden coffin as it began its journey to her hometown, Larkana, in southern Pakistan, for burial. In Karachi and other cities, frenzied crowds vented their rage, blocking the streets, burning tires and throwing stones.

The death of Ms. Bhutto, leader of Pakistan’s largest political party, throws Pakistan’s politics into disarray less than two weeks before parliamentary elections scheduled for Jan. 8 and just weeks after a state of emergency was lifted. There was immediate speculation that elections would be postponed and another state of emergency declared.

A deeply polarizing figure, Ms. Bhutto spent 30 years navigating the turbulent and often violent world of Pakistani politics, becoming in 1988 the first woman to lead a modern Muslim country.

She had narrowly escaped an assassination attempt upon her return to Pakistan two months ago. Her death now presents President Pervez Musharraf with one of the most potent crises of his turbulent eight years in power, and Bush administration officials with a new challenge in their efforts to stabilize a front-line state – home to both Al Qaeda and nuclear arms – in their fight against terrorism.

The attack bore hallmarks of the Qaeda-linked militants in Pakistan. But witnesses described a sniper firing from a nearby building, raising questions about how well the government had protected her in a usually well-guarded garrison town and fueling speculation that government sympathizers had played a part.

On Thursday evening, officials from the Federal Bureau of Investigation and the Department of Homeland Security issued a bulletin to local law enforcement agencies informing them about posts on some Islamic Web sites saying that Al Qaeda was claiming responsibility for the attack, and that the plot was orchestrated by Ayman al-Zawahri, the group’s second-ranking official.

One counterterrorism official in Washington said that the bulletin neither confirmed nor discredited these claims. The official said that American intelligence agencies had yet to come to any firm judgments about who was responsible for Ms. Bhutto’s death.

As world leaders lined up to express outrage at the killing of arguably Pakistan’s most pro-Western political figure, a grim-faced President Bush said that the best way to honor her would be “by continuing with the democratic process for which she so bravely gave her life.”

Speaking to reporters while vacationing at his ranch in Crawford, Tex., Mr. Bush attributed Ms. Bhutto’s death to “murderous extremists who are trying to undermine Pakistan’s democracy.” He telephoned Mr. Musharraf several hours after the attack.

Mr. Musharraf went on national television on Thursday evening, describing the killing as “a great national tragedy” and announcing a three-day national mourning. He called it a terrorist attack and vowed to continue to fight to root out the terrorists. “I appeal to the nation to remain peaceful and show restraint,” he said.

Despite the president’s appeal, politicians and government officials said they feared more violence in the coming days from those protesting her death, but also from militants who would try to take advantage of the uncertain situation.

One former government minister said the backlash against Mr. Musharraf could make his position untenable. “Musharraf will not be able to control the situation now,” he said.

Before her return in October, Ms. Bhutto had spent nearly eight years in self-imposed exile to avoid corruption charges stemming from her time as prime minister in the 1990s. Her return had been promoted by Washington as part of an agreement to share power with Mr. Musharraf and rescue his increasingly unpopular government by giving it a more democratic face.

She was a leading contender for prime minister in the Jan. 8 elections, campaigning as an advocate for Pakistan’s return to party politics after eight years of military rule under Mr. Musharraf, who relinquished his military post only this month. She also presented herself as the candidate who could best combat growing militancy in Pakistan.

Her comments condemning militancy and suicide bombing had made her a target of Qaeda-linked militants in Pakistan. Her homecoming procession in Karachi was attacked by two bomb blasts that killed 150 supporters and narrowly missed killing her.

Much of the rage over her death is nonetheless likely to be directed at Mr. Musharraf, who kept her out of power for over eight years and had shown her only a grudging welcome at first, and later outright hostility.

The country’s other main opposition leader, another former prime minister, Nawaz Sharif, announced Thursday evening that he was pulling his party out of the elections. A longtime political rival of Ms. Bhutto’s, he had lately become an ally in pressing for a return to democracy in Pakistan.

“This is a tragedy for her party, and a tragedy for our party and the entire nation,” Mr. Sharif said as he visited the hospital on hearing the news of her death.

Tauqir Zia, a retired general who recently joined Ms. Bhutto’s party, the Pakistan Peoples Party, said it seemed that elections were unlikely to go ahead now in any case. “P.P.P. is now in turmoil for the time being,” he said. “It has to find a new leadership.”

Other officials and politicians said they, too, thought elections would have to be postponed. “This is going to lead to chaos and turmoil,” said the former interior minister, Aftab Ahmed Khan Sherpao, who was nearly killed last week in a suicide bombing at a mosque in his home village. “I was anticipating this, that suicide bombings would increase and there will be an exacerbation and intensification in the attacks. This was bound to happen.”

There were differing accounts of the attack. Zamrud Khan, a member of her party, said Ms. Bhutto was shot in the head from gunfire that originated from behind her car in a building nearby. Seconds later a suicide bomber detonated his bomb, damaging one of the cars in her motorcade and killing some 15 people on the ground, Mr. Khan said.

The Interior Ministry spokesman quoted by the state news agency, The Associated Press of Pakistan, said that the suicide bomber first fired on Ms. Bhutto and then blew himself up.

Amid the confusion after the explosion, the site was littered with pools of blood. Shoes and caps of party workers were lying on the asphalt. More than a dozen ambulances pushed through crowds of dazed and wounded people at the scene of the assassination.

Witnesses described hearing gunfire barely a minute before the loud explosion. Sajid Hussain, who had a shrapnel wound on his left hand, said he heard at least three shots fired. “Then there was a big explosion, the earth seemed to tremble, I fell down. And everything was covered in black smoke.”

Mr. Zia, the retired general, said he was sitting in a car ahead of Ms. Bhutto before the blast. “A leader has to come out and lead and she did exactly that,” he said. “But I would ask where was the security? How did they allow people to come so close to her? It is inconceivable. There is a definite lapse of security.”

Dr. Abbas Hayat of Rawalpindi General Hospital said that doctors tried for 35 minutes to resuscitate Ms. Bhutto, who he said had wounds to her head as well as shrapnel injuries.

Dr. Mohamed Mussadik, head of the medical college in Rawalpindi and a top surgeon who attended to Ms. Bhutto at the hospital, said she was clinically dead on arrival, according to Athar Minallah, a lawyer who served in the Musharraf government but who has since helped lead the movement against him. In a telephone interview, Mr. Minallah said Dr. Mussadik had told him that the bullet wound was in the head.

Mr. Minallah said an independent, credible investigation into the assassination was critical, perhaps in partnership with an outside country. A precedent for this, he said, was the investigation into the murder of Ms. Bhutto’s brother 11 years ago. “The government has to allow it,” he said, “because the entire blame is on the government. Everyone I have spoken to believes it is the government that has done this. That makes the investigation of utmost importance.”

Apparently no autopsy was done, because the police did not request one, Dawn TV reported. Lawyers calling for an international neutral investigation are raising questions about the speed with which Ms. Bhutto’s body was moved. The body arrived in her southern home province of Sindh before dawn, party officials told Agence-France Presse.

The assassination is likely to deepen suspicion among Ms. Bhutto’s supporters of Pakistan’s security agencies. Ms. Bhutto has long accused parts of the government, namely the country’s premier military intelligence agency, the Inter-Services Intelligence, or ISI, of working against her and her party because they oppose her liberal, secular agenda.

In a letter she sent to Mr. Musharraf just before her return to Pakistan in October, she listed “three individuals and more” in the letter who should be investigated for their sympathies with the militants in case she was assassinated.

An aide close to Ms. Bhutto said that one of those named in the letter was Ijaz Shah, the director general of the Intelligence Bureau, another of the country’s intelligence agencies and a close associate of General Musharraf’s.

The second official was the head of the country’s National Accountability Bureau, which had investigated Ms. Bhutto on corruption charges. The third was a former official in Punjab Province who had mistreated her husband, Asif Ali Zardari, when he was in jail awaiting trial on corruption charges.

In an interview after Ms. Bhutto released the letter, a close aide to Mr. Musharraf said the people named in the letter were all political enemies of Ms. Bhutto. He said they did not have sympathy with militants and the government was doing all it could to protect Ms. Bhutto.

A former senior Pakistani intelligence official said he did not believe that the country’s intelligence agency was involved. He blamed militants for the assassination, but said government-provided protection was far too lax and the area surrounding the rally should have been better secured.

“For sure, the government was complicit in the security aspects,” said the official, who spoke on condition of anonymity. “I think the security arrangements of the police, they were not professionally handled.”

Salman Masood reported from Rawalpindi, Pakistan, and Carlotta Gall from Kabul, Afghanistan. Reporting was contributed by Ismail Khan from Peshawar, Pakistan, Mark Mazzetti from Washington, David Rohde from New York and Jane Perlez from Sydney, Australia.