Pakistani opposition leader Benazir Bhutto was killed in a gun and bomb attack after a rally in the city of Rawalpindi on Thursday, her party said.
"She has been martyred," said party offical Rehman Malik.
Police at the scene said about 15 people had been killed.
A Reuters witness said he saw about eight bodies on a road as well as a mutilated human head.
An Interior Ministry spokesman said initial reports suggested it was a suicide bombing and more than 10 people had been killed.
A suicide bomber killed nearly 150 people in an attack on Bhutto on Oct. 18 as she paraded through the southern city of Karachi after returning home from eight years in self-imposed exile.
Earlier, gunmen opened fire on supporters of another former prime minister, Nawaz Sharif, from an office of the party that supports President Pervez Musharraf, killing four Sharif supporters, police said.
Sharif was several kilometres away from the shooting and was on his way to Rawalpindi after attending a rally.
Sharif, who was overthrown by Musharraf in a 1999 coup and allowed back into the country just last month after seven years in exile, blamed supporters of the pro-Musharraf party for the violence.
To be honest, I considered Bhutto to be a corrupt political leader who almost certainly defrauded her people of billions, and who tried her best to ink a deal with the dictator Musharraf in order to share power with him.
To quote Jemima Khan, wife of Imran Khan, a pro-democracy political oponent of Bhutto:
"She's totally bogus - Benazir may speak the language of liberalism and look good on Larry King's sofa ... but she's as ruthless and conniving as they come. She's a kleptocrat in a Hermes scarf."
...and yet, sadly, she was Pakistan's most likely choice for the restoration of democracy, such as it was... such as they knew it.
My only hope is that this will lead Pakistanis to renounce violence, to reject their current leaders, and lead them towards other leaders, who are "the real thing".