A man in a wheelchair trying to cross a freeway transition ramp in La Mesa was struck by a car and killed Sunday night, officials said. The man was hit around 9:50 p.m. by a driver in a white Mercedes while he was attempting to cross the transition ramp from eastbound Interstate 8 to state Route 125, California Highway Patrol Officer Jared Grieshaber said. The driver was traveling about 45 mph when the collision occurred, officials said. The pedestrian suffered major injuries and was transported to a hospital, where he died, Grieshaber said. The name of the man who died was not immediately released. The driver remained at the scene and talked to CHP investigators. Grieshaber said the investigation was ongoing.