A huge explosion, caused by a truck bomb, rocked the headquarters of the Italian military police in the southern Iraqi city of Nassiriya shortly before 11:00 a.m. Wednesday, killing at least 17 Italians and nine Iraqis, according to the Italian military. Some 15 people were injured, although their nationalities were not known, Italian officials said. "I can tell you there was a big explosion," Italy's Captain Marco Mele told Reuters a few minutes after the blast. In Rome, meanwhile, the spokesman of the Commander General of the Italian military police said "A bomb exploded in front of the military police base of MSU (Multinational Specialized Unit) ... there are many wounded among our troops and among the Iraqis." Later, in Rome, Italy's Defense Minister Antonio Martino confirmed 17 Italians were killed: 12 Carabinieri paramilitary police, four Army soldiers, and an Italian civilian working at the base. The explosion occurred after a truck rammed the gate of the Italian compound and exploded in front of the Carabinieri building, which was the former chamber of commerce building. Secondary blasts from ammunition stored in the compound rocked the area moments after the main explosion. It was the first such attack in this city since the beginning of the U.S.-led occupation. Italian President Carlo Azeglio Ciampi called the bombing a "terrorist act." The Italian premier, Silvio Berlusconi, pledged that it wouldn't derail Italy's commitment to helping Iraq's reconstruction efforts. Elsewhere, five Iraqi civilians died and four others were injured when U.S. troops opened fire on a truck at the entrance of Fallujah, police said Wednesday. The U.S. military could not confirm the incident that police said took place late Tuesday in Fallujah, 50 kilometers from the capital. "The U.S. forces had erected a checkpoint at the entrance of Fallujah to catch thieves who have been stealing steel from a nearby factory," police Major Assaad Abdul Karim told AFP. "When the truck came near the American base at around 9:00 pm last night, they apparently thought they were steel thieves, so they opened fire and killed five of them and injured four others," he said. "This is a wrongful action," he charged. Moreover, Abdul Karim said the U.S. forces "asked us to come to their base today (Wednesday) to take the bodies of the five people killed and the four other people wounded." Also Wednesday, American soldiers in Baghdad accidentally fired on a car carrying a member of the Iraqi Governing Council. The council member, Mohammed Bahr al-Uloum, escaped injury but the driver was wounded. **PHOTO CAPTION*** Iraqi policemen and rescue workers at the wreckage of the Italian army headquarters in Nasiriyah. (AFP/Carabinieri/ANSA)