Pakistan opposition leader Benazir Bhutto was killed by a suicide bomber as she left a public rally.
Ms Bhutto, twice the country's prime minister, was caught by the blast as she was driven from the rally in the city of Rawalpindi.
"At 6.16pm she expired," said Wasif Ali Khan, a member of Bhutto's party who was at Rawalpindi General Hospital.
A senior military official confirmed that Ms Bhutto had died in the explosion that also killed at least another 20 people.
She had just addressed thousands of people in a public park as part of her campaign for the country's parliamentary elections, which are due on January 8.
Her supporters at the hospital began chanting "Dog, Musharraf, dog," referring to Pakistan's president, Pervez Musharraf.
Some of them smashed the glass door at the main entrance of the emergency unit, others burst into tears.
Her lawyer said: "The surgeons confirmed that she has been martyred."
Ms Bhutto ,54, served twice as Pakistan's prime minister between 1988 and 1996. She had returned to Pakistan from an eight-year exile last October after agreeing an amnesty deal with President Musharraf over corruption charges.
Her homecoming parade in Karachi was also targeted by a suicide attacker, killing more than 140 people. On that occasion she narrowly escaped injury.
