U.S. forces in Iraq have fired on a car carrying a newly freed Italian hostage, wounding her and killing an Italian security officer. A US. military statement says soldiers shot on the car carrying journalist Giuliana Sgrena when the driver failed to obey orders to stop at a military checkpoint. Italian Prime Minister Silvio Berlusconi said Ms. Sgrena was wounded in the shoulder, and an Italian agent who helped free her was killed. The White House says President Bush expressed regret over the incident in a telephone call to Mr. Berlusconi and promised a full investigation. Ms. Sgrena is a correspondent for the Il Manifesto newspaper. Gunmen kidnapped her in Baghdad on February fourth, demanding Italian troops leave Iraq. Also Friday, four U.S. Marines were killed during an operation in al-Anbar province and a Bulgarian solder was killed in an insurgent attack in central Iraq.