A teenage motorist fired at an off-duty University of Houston-Downtown police officer who offered help for his stalled vehicle early today, police said. Officer Jaime Cortez was trying to drive around the car in the 5700 block of Broadway about 1:45 a.m. when he rolled down his window and asked if the 16-year-old driver needed help. HPD investigators said Cortez was not in uniform and didn't identify himself as an officer. The teenager apparently was offended by the gesture and fired three rounds, striking the officer's car once, police said. Cortez then followed the vehicle to a motel in the...