Angry supporters also took to the streets in the northwestern city of Peshawar as well other areas, chanting slogans against Musharraf.
In Rawalpindi, the site of the attack, Bhutto’s supporters burned election posters from the ruling party and attacked police, who fled from the scene.
Nawaz Sharif, another former premier and leader of a rival opposition party, rushed to the hospital and addressed the crowd.
“Benazir Bhutto was also my sister, and I will be with you to take the revenge for her death,” he said. “Don’t feel alone. I am with you. We will take the revenge on the rulers."
Next to President Pervez Musharraf, Bhutto, 54, was the best known political figure in the country, serving two terms as prime minister between 1988 and 1996.
The United States condemned the attack.
A US State Department official said: “The attack shows that there are still those in Pakistan trying to undermine reconciliation and democratic development in Pakistan.”