A roadside bomb exploded Sunday near a gas station in northern Baghdad, wounding three civilians, police said. The blast went off around 7 a.m., as people were lining up to buy fuel at the start of the work week here. About half an hour earlier, another roadside bomb struck an American military patrol in a northeastern section of the Iraqi capital, police said. A US humvee caught fire, but there was no word on any casualties, police said. Iraqi police also said US helicopter gunships bombed a truck in eastern Baghdad around 8 a.m. The truck had apparently been carrying a rocket launcher, they said.