At least seven people have been killed in the Afghan capital Kabul after a traffic accident involving a US military convoy sparked mass rioting.
Hundreds of anti-US protesters clashed with Afghan security forces for two hours, in one of the worst riots since the fall of the Taleban in late 2001.
The protesters moved on to attack buildings in the diplomatic quarter.
There are conflicting reports over whether the US troops in the military convoy fired into the crowd.
Police and armed forces moved in to restore law and order and an overnight curfew was declared.
But there is an underlying nervousness that more anti-American demonstrations and violence will follow, the BBC's Alastair Leithead in Kabul says.
Afghan President Hamid Karzai appeared on live television to urge people to "stand up against these agitators and not let them destroy our country again".
The unrest began after a US military vehicle apparently lost control and smashed into at least 12 civilian cars during morning rush-hour in Kabul's northern suburbs.
Coalition spokesman Col Thomas Collins said a large cargo truck in the US convoy had suffered a mechanical failure, hitting the cars at a busy junction.
"This was a tragic accident and we deeply regret any deaths or injuries resulting from this incident," he said, adding that a full investigation was under way.
Hundreds of Afghans gathered after the accident, chanting "Death to America" and "Death to Karzai".
They pelted the US military vehicles with stones before scattering when the shooting began.
Some eyewitnesses say the US troops shot at protesters, while others say it was the Afghan police, who had come to the aid of the under-siege convoy. Some say it was both.
The US military said there were "indications" that at least one of the vehicles in the convoy "fired warning shots over the crowd".
The military said at least one person was killed and six injured in the traffic accident, although local police put the figure at three dead and 16 injured.
The number of dead and wounded from the rioting is also confused, with some reports putting the death toll at up to 20 with more than 100 injured.
As many as 2,000 protesters then headed for the city centre, towards the presidential palace and parliament, setting fire to police cars and police checkpoints.
Hundreds of protesters took to the streets
Bursts of heavy gunfire could also be heard close to the US embassy, whose staff were moved to a secure location.
At the height of the violence, 21 European Union diplomats and staff had to be rescued from their compound by British Royal Marines working for the Nato-led International Security Assistance Force (Isaf).
Buildings were ransacked and set alight, including the compound of the aid organisation Care International.
A spokesman for the London-based charity said they were assessing the damage and "the implications for our work in the country" but did not believe Care had been specifically targeted "as we have good relations with the local community".
Separately, Afghan officials say fighter planes of the US-led coalition have attacked suspected Taleban fighters in the south of the country.
The deputy governor of Helmand province, Amir Mohammed Akhundzada, said he believed about 50 militants were killed in the attack.
"The Taleban were meeting in a mosque when the bombardment took place," Mr Akhundzada told Reuters news agency.
He said police had yet to reach the site to confirm any figures.