"We are prepared to risk our lives. We're prepared to risk our liberty. But we're not prepared to surrender this great nation to militants," Bhutto told a news conference in Karachi.
The 54-year-old former prime minister returned after eight years of self-imposed exile Thursday to lead her Pakistan People's Party into national elections that are intended to shepherd a transition from military to civilian-led democracy.
Bhutto said there were two attackers in the deadly blasts, and that her security team found a third man armed with a pistol and another with a suicide vest. Ahead of her arrival in Pakistan, she said, she was warned suicide squads were assembled to kill her.
"There was one suicide squad from the Taliban elements, one suicide squad from al-Qaida, one suicide squad from Pakistani Taliban and a fourth -- a group -- I believe from Karachi," she told reporters, according to news agency accounts. Bhutto said telephone numbers of suicide squads had been given to her by a "brotherly" country and that she had alerted President Gen. Pervez Musharraf in a letter dated Oct. 16., the Associated Press reported.
She did not blame the government, but said it was suspicious that streetlights failed after dark Thursday when her convoy was inching its way through the crowded streets of Karachi. She said the phones were also down, making it difficult to have the lights restored, according to the AP.
"I'm not accusing the government but certain individuals who abuse their positions and powers," Bhutto said. "We were scanning the crowd with the floodlights, but it was difficult to scan the crowds because there was so much darkness."
There was no claim of responsibility for the attack, which put new strain on future negotiations between Bhutto and Musharraf for a power-sharing deal in which they would lead a moderate, pro-U.S. alliance. Officials at six hospitals in Karachi reported 136 dead and around 250 wounded.