The riots began after a U.S.-led coalition truck crashed in Kabul, killing at least five people. In a televised speech on the riots, Karzai said Afghans must stand up against "agitators" who loot and destroy property.
Hundreds of Afghans took to the streets and gunfire broke out in central Kabul today after a coalition truck crashed in rush-hour traffic. Early, unconfirmed reports say U.S and Afghan troops may have fired on a threatening crowd, killing and injuring others.
Buildings and vehicles were set ablaze and shops closed in Kabul as protests targeted the United States and the central Afghan government. Reports say some shops were looted. A police station, police vehicles, and other cars were set on fire.
Afghanistan's presidential office released a statement saying five people were killed in the traffic accident.
A U.S. military spokesman said coalition troops may have fired towards hostile demonstrators.
"The [U.S.-led] coalition is conducting a full investigation regarding this incident," spokesman Tom Collins said. "There have been reports of gunfire at the scene. There are indications that at least one coalition military vehicle fired warning shots over the crowd."
Collins says the U.S.-led coalition regrets any deaths or injuries that resulted from the automobile accident. Karzai said: "we are deeply saddened by the loss of civilian lives" and promised that the Afghan government will help the families of the victims.
Protesters marched toward the presidential palace and near the U.S. and British embassies. Hundreds of Afghan security forces and NATO troops were deployed around the city to try to control the situation.
The Afghan Interior Ministry and parliament have called for calm in the face of the mounting riots. And erratic gunfire was reported in the capital.
As the riots gained momentum this afternoon, parliamentary speaker Mohammad Yunos Qanuni urged protesters to be patient and to let the government handle the situation.
A U.S.-led coalition spokeswoman, Lieutenant Tamara Lawrence, said the trouble began this morning when a vehicle in a U.S. convoy went out of control, smashing into other cars. In addition to the deaths, several others were injured.
As a crowd gathered, people reportedly began throwing stones at the U.S. vehicle.
Rioting quickly followed, as the crowd swelled in size. Shots were fired in the ensuing chaos, although it is unclear whether the gunfire came from Afghan or U.S. troops.
The outcry appeared to take on a more broadly political tone as marchers chanted anti-U.S. and antigovernment slogans. Protesters neared the palace that houses President Hamid Karzai, and embassy buildings.
Reuters reports that dozens of protesters forced through a police cordon around a road leading to the U.S. Embassy, throwing stones at passing vehicles.
One of the protesters, Jaweed Agha, spoke to Reuters. "We don't accept Karzai as president anymore, and we protest against him," he said.
Later in the day in the television broadcast, Karzai described the rioters as "enemies of Afghanistan."
Afghan National Army troops and police have been deployed around Kabul to prevent people from entering the city.
U.S. forces have been placed in lockdown -- with troops reportedly prevented from leaving U.S. or coalition facilities.