At least six Iraqis and five US soldiers have been killed in fresh clashes in Samarra, north of the capital, according to US military and hospital sources. The fresh unrest in Samarra, 125 km north of Baghdad, started just before 11 am (0700 GMT) when the Iraqi national guard headquarters at the entrance of the city was attacked with some 35 mortars. The attack caused the collapse of the headquarters, a US military spokesman said. "There was a mortar attack on the Iraqi national guard headquarters in Samarra. They fired four mortar rounds striking and collapsing the building, used by the national guard and 1st Infantry Division (ID) soldiers," said spokesman Major Neal O'Brien. **Explosion*** A former Baath party official was killed on Thursday when a bomb hidden in his car exploded outside the Baghdad rope factory that he owned, police said. Iraqi police and US troops sealed off the area where the man's charred remains lay by the burnt wreckage of his vehicle, destroyed when the booby trap detonated. "He was getting into his car when it exploded," said Anmar Yassine, the senior police officer at the scene, a street in an industrial district in the south of the capital. The victim, Ali Abbas, had been the treasurer of a regional committee of ousted President Saddam Hussein's Baath party. **Ambush*** In Baghdad, national guardsmen were ambushed for the second time in less than 24 hours, killing an Iraqi soldier in a street battle, the US military said on Thursday. "One guardsman was killed and 12 wounded" in the fighting which broke out around 10 pm (18:00 GMT) on Wednesday, a military spokesman said. The US army was called in to reinforce the Iraqi national guardsmen and help beat back the assailants, the military said. "The 1st Cavalry Division detained nine anti-Iraqi forces and killed a rocket-propelled grenade gunner," the spokesman said. **Earlier ambush*** The shootout came after an ambush on national guardsmen on Wednesday morning in central Baghdad, killing two guardsmen and wounding 21 others. But four Iraqis were injured earlier in the day when clashes erupted between US patrol and unidentified armed assailants in the Abu Ghraib district west of Baghdad. Aljazeera's correspondent said the aftermath of the fighting resulted in burnt out and damaged shops. The area was then sealed off as US troops searched for the assailants. **PHOTO CAPTION*** Marwan Hassoun, 23, looks to the spot in Samarra, Iraq Tuesday, July 6, 2004 where his cousin Zaidoun Faleh Hassoun drowned after U.S. soldiers pushed him into the water Jan. 3, 2004. (AP)