Pakistani opposition leader Benazir Bhutto has been shot dead at an election rally - sparking riots across the country.
Crowds carry former PM's coffinThe gunman then detonated a bomb, killing at least 15 of her supporters in Rawalpindi. Many more were injured in the suicide blast.
At least four people have been shot dead in rioting as fears grow the nuclear-armed country will be plunged into civil war.
In Karachi, capital of Ms Bhutto's native Sindh province, thousands took to the streets, torching dozens of vehicles and buildings.
"There is trouble almost everywhere," a senior police official said.
The killing came less than two weeks before elections many expected would return Ms Bhutto to power and restore democracy.
Nawaz Sharif, the leader of a rival opposition party, vowed revenge and said his party would boycott the January 8 poll.
He told crowds: "Benazir Bhutto was also my sister, and I will be with you to take the revenge for her death. Don't feel alone. I am with you. We will take the revenge on the rulers."
Leaders around the world condemned the assassination as Pakistan announced three days of mourning.
In an emergency session, the UN Security Council voted unanimously to track down those behind the "reprehensible act".
Britain's Prime Minister Gordon Brown said: "She has been assassinated by cowards afraid of democracy. This attack strengthens our resolve that terrorists will not win."
Bhutto...minutes before her deathUS President George Bush said those responsible for the killing must be brought to justice.
He added: "The US strongly condemns this cowardly act by murderous extremists who are trying to undermine Pakistan's democracy."
An FBI bulletin sent to law enforcement agencies in the US is reported to have cited Islamist web sites as saying al Qaeda carried out the attack and that the terror network's number two, Ayman al-Zawahri planned it.
Ms Bhutto was shot in the chest and neck as she got into her car after her speech to thousands in Rawalpindi.
Killing sparks riots in PakistanThe former PM was unconscious as she was taken to Rawalpindi General Hospital and died soon after. Her body is being taken to her home town in Larkana.
"She has been martyred," said Rehman Malik, a spokesman for her party.
Some of her supporters smashed windows and doors at the hospital, chanting: "Dog, Musharraf, Dog."
It is the first major attack since President General Pervez Musharraf lifted emergency rule two weeks ago.
He has appealed for calm in the country and declared three days of mourning.
But there have already been riots in cities across Pakistan, and Sky News Asia correspondent Alex Crawford believes there is more bloodshed to come.
She said the country's January 8 elections would now "most likely be postponed or cancelled".
She added: "Hopes of democracy have pretty much been killed before they had the chance to flower."
Rehman Malik, Ms Bhutto's security advisor, said: "We repeatedly informed the government to provide her proper security and appropriate equipment including jammers, but they paid no heed to our requests".
But Pakistan's ambassador in the US rejected accusations that more could have been done to protect her.
This is a very sad turn of events, indeed.