Baghdad, Iraq ? Iraqi police opened fire Wednesday in the heart of Baghdad and in northern Iraq to disperse protesters complaining of corruption in the distribution of scarce jobs. A U.S. soldier was killed in a roadside bombing near the main U.S. base in Saddam Hussein’s hometown, and another American was shot dead in Baghdad.

Also Wednesday, American soldiers fired warning shots over the heads of stone-throwing Shiite Muslims outside a mosque in Baghdad. The Shiites were angry about the brief detention of their preacher, who they said was questioned about allegedly inflammatory sermons.

The Shiites warned if they did not receive a written apology from the Americans and Iraqi police within three days, they would turn against the U.S. occupation.

Gunfire rattled Wednesday morning through the streets of downtown Baghdad after about 1,000 protesters stormed a police station near the Palestine Hotel to demand jobs with the Iraqi police force. Many said they paid bribes to have their names added to the recruit list but had not been hired.

After protesters set fire to two cars, police opened fire, sending demonstrators, motorists and pedestrians scurrying for cover. At least one police officer was seen firing his pistol into the crowd. Witnesses said two people were injured.

The U.S.-led coalition faced more attacks by Iraqis opposed to the American presence. In the latest attack, a roadside bomb exploded about 300 yards from the main U.S. base in Saddam’s hometown, Tikrit, killing a female soldier and wounding two other Americans, officials said.

Late Wednesday, a soldier from the 1st Armored Division was shot and killed while on patrol in the al-Mansour district of western Baghdad, the U.S. command said.