Rehman Malik, an official with Bhutto's Pakistan People's Party, announced Bhutto's death to supporters: "She has been martyred."
, the Pakistani opposition leader, vowed to continue Bhutto's work after the assassination and said he shared the grief of "the entire nation".
Speaking outside the hospital where Bhutto died he said: "I assure you that I will fight your war from now on," he told Bhutto's supporters. "I share your sorrow and grief along with the entire nation."
"Benazir Bhutto was also my sister, and I will be with you to take the revenge for her death," he said.
Pervez Musharraf, the Pakistani president, appealed on state television for the nation to remain peaceful "so that the evil designs of terrorists can be defeated".
George Bush, the US president, said: "The US strongly condemns this cowardly act by murderous extremists who are are trying to undermine Pakistan's democracy."
"We stand with the people of Pakistan in that struggle against the forces of terror and extremism. We urge them to honour Benazir Bhutto's memory by continuing with a democratic process."
Ban Ki-moon, the UN Secretary general, said: "I strongly condemn this heinous crime and call for the perpetrators to be brought to justice as soon as possible."
Manmohan Singh, India's prime minister, said:"I was deeply shocked and horrified to hear of the heinous assassination. In her death, the subcontinent has lost an outstanding leader who worked for democracy and reconciliation in her country."
"In targeting Benazir Bhutto extremist groups have in their sights all those committed to democratic processes in Pakistan. They cannot and must not succeed"
British foreign secretary
, the British foreign secretary, said: "I am deeply shocked by news of the latest attack in Rawalpindi which has claimed the life of Benazir Bhutto and killed at least 15 other people ... All those committed to a stable future for Pakistan will condemn without qualification all violence perpetrated against innocent people.
"In targeting Benazir Bhutto extremist groups have in their sights all those committed to democratic processes in Pakistan. They cannot and must not succeed."
Qin Gang, China's foreign ministry spokesman, said China was "shocked at the killing of Pakistan's opposition leader Benazir Bhutto" and that strongly condemns the terrorist attack," Xinhua news agency said.
Romano Prodi, the Italian prime minister, said : "I express my sadness and that of the whole [Italian] government following the tragic death of Benazir Bhutto, a woman who wanted to fight her battle until the end with just one weapon - that of dialogue and political discussion."
The Vatican called the assassination "terrible and tragic."
"This attack shows how extremely difficult it is to pacify a nation so wrought by violence," Father Frederico Lombardi, the Vatican spokesman said. "We share the sadness of the Pakistani population."
Ameen Jan, a London-based political analyst, told Al Jazeera: "Removing Benazir Bhutto from the political scene, there would be many beneficiaries of that ... Having said that it would be difficult to imagine that the perpetrators behind such a violent attack, leading to her death, would be one of the political parties."
"There are a whole set of actors outside of the mainstream political parties which are the various extremist groups, and it would seem more than likely that there would be some elements within those groups that would have an interest in destabilising the political system," he said.
General Talat Masood
"It's a great shock for the nation and its a great set back to the democratic forces and to politics in Pakistan"
General Talat Masood,
, a military analyst in Islamabad, speaking to Al Jazeera, said: "It's a great shock for the nation and its a great set back to the democratic forces and to politics in Pakistan. Her party [the PPP] was one of those that was spearheading the political process ... and this party was very leader-centric. They really adored and loved her despite all her weaknesses ... neither the militants nor those in power ever like a person of her calibre."
"You could see the crowds she was drawing and the likelihood of her party doing extremely well, that was there. But it also shows that when the US intervenes it always has a negative fallout on countries."
Jennifer Harbison, head of the Asia Desk at Control Risks in London, said: "I think this is anticipated. It is well within what we expected might happen ... It does cast a shadow over the election and it raises some concerns over how the government might deal with any popular reaction to this."
Khaled Rahmen, director general of the Institute of Policy Studies in Islamabad, told Al Jazeera: "It's a very sad incident ... and such a big incident would definitely impact the elections. There are apprehensions that this might result in some kind of postponement. If that happens ... its going to create more instability."
Max King, London-based investment strategist with Investec Asset Management, said: "This is an absolute disaster for Pakistan. Pakistan is clearly turning into one of the failed states in Asia."