Authorities in Afghanistan have imposed a strict night curfew throughout the capital, Kabul, following anti-American riots triggered by a fatal car accident involving a U.S. convoy.  At least 13 people were left dead, and dozens of others seriously wounded.

An Afghan protester prepares to throw stones at a U.S. military convoy in Kabul, Afghanistan, Monday, May 29, 2006

Violent protests spread throughout the capital, Monday. Witnesses say it is the worst civil unrest in Kabul since coalition forces ousted the Taleban in 2001.

The rioting started after an American military truck accidentally slammed into as many as a dozen civilian vehicles Monday morning. Local officials say the crash killed at least five people and injured several others.

Within minutes, protests erupted near the wreckage, and hundreds of people began throwing rocks and debris at the U.S. soldiers.

As local police struggled to regain control of the area, shots were fired.

A number of witnesses say they saw U.S. soldiers open fire, while others say local police were responsible for the casualties.

U.S. Military spokesman Colonel Thomas Collins says American troops fired only warning shots into the air, as the crowd tried to surround their vehicles.

"When the gathering became hostile, the coalition vehicles attempted to move out of the area to reduce tensions," said Colonel Collins. "There are indications that at least one coalition military vehicle fired warning shots over the crowd."

By mid-day, hundreds of protesters took to the streets in several locations around the capital. Automatic gunfire could be heard across the city.

Demonstrators marched through the streets, shouting abuse at the United States and the U.S.-backed president, Hamid Karzai. Some chanted "Death to America!" and "Death to Karzai."

Rioters ransacked a number of stores, and reportedly attacked the offices of a western aid agency.

Afghan security forces and NATO peacekeepers, many of them in tanks, have been deployed throughout the city.

President Karzai delivered a televised address to the nation Monday afternoon appealing for calm.

[He called on the Afghan people to stand up against rioters and described them as "agitators" and enemies of Afghanistan] 

The central government imposed a strict curfew throughout the capital until Tuesday morning to prevent further violence.

In recent weeks a rising number of civilian casualties in anti-terror operations in Afghanistan has led to widespread concerns that this is undermining President Karzai's popular support throughout the country.