SAN FRANCISCO — San Francisco police say a 17-year-old boy was killed and two others seriously injured when an elderly woman driving at speeds of up to 80 mph slammed into their minivan, causing both vehicles to roll over.

The crash occurred just before 7 a.m. Friday. Police say the minivan was stopped at a light when it was struck from behind by the woman's Mercedes Benz.

The boy was killed. His mother and a sibling suffered serious injuries.

Three people in a catering van that was also struck suffered non-life-threatening injuries.

The Mercedes Benz driver suffered minor injuries.

Police Chief Greg Suhr says witnesses told investigators she had been speeding before the crash. She was not arrested and has not been identified.