A 20-year-old Modesto woman was killed Sunday after her Ford Explorer crashed on southbound Highway 99 near Atwater, the California Highway Patrol reported. The Merced County coroner's office did not release her name. A 28-year-old Atwater man who was a passenger in the vehicle received minor to moderate injuries and was taken to Doctors Medical Center in Modesto. The crash was reported at 2:40 a.m. after the driver had been traveling in a 2002 Ford Explorer at a high rate of speed. The driver veered to the right and traveled off the highway, onto the right shoulder, said Shane Ferriera, a CHP spokesman. He said the vehicle traveled down an embankment, hit a roadway sign and traveled back toward the freeway. The vehicle overturned several times before coming to a stop. Ferriera said investigators are looking into whether alcohol was a factor in the crash.