A 25-year-old police officer was struck and killed after she stopped to help a motorist in an overturned vehicle on a San Diego freeway on Monday night, authorities said. La Mesa Police Officer Lauren Craven was on her way back to La Mesa from a jail around 10:30 p.m. when she came across the vehicle on Interstate 8 and stopped to assist, according to a statement from police. After exiting her vehicle to help, she was hit by another driver.