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.
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 intersection.
"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 came 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".
and remember kids, like George Bush said, its all freedom and democracy now in Afganistan.
US President George W Bush has praised the progress of Afghan democracy on his first visit to the country, where the US helped eject the Taleban in 2001.
On a surprise first stop of his maiden trip to South Asia, Mr Bush told Afghan President Hamid Karzai his country was "inspiring others".
He said he was still confident Osama Bin Laden would be brought to justice.