Afghanistan's President Hamid Karzai has fired at least 24 top police officials days after anti-U.S. riots in Kabul.

Officials said Saturday the shake-up includes Kabul's police chief, whose forces failed to prevent rioters from looting stores and setting fire to offices and cars in the capital.

The riots erupted Monday after a U.S. military truck accidentally crashed into civilian vehicles.

U.S. military spokesman Tom Collins said an initial probe shows that mobs threw stones and fired shots after the accident, and that U.S. troops fired back in self-defense.

Afghan police say at least 20 people were killed and 160 wounded in the accident and subsequent unrest.

White House spokesman Tony Snow said President Bush spoke to Mr. Karzai and pledged an investigation.

Some information for this report was provided by AFP and Reuters.