SAN DIEGO -- A Caltrans employee and one of several probationers she was overseeing on a trash pickup job were seriously injured Thursday when a car hit them alongside Interstate 15 in City Heights, authorities said.

The northbound 1992 Infiniti J30 veered off the right-hand side of the freeway just south of the Interstate 805 interchange and struck the back of a slow-moving Caltrans van on the shoulder of the roadway shortly after 10:30 a.m., according to the California Highway Patrol.

The sedan caromed off the larger vehicle before hitting the man and woman working in front of it, CHP public affairs Officer Brad Baehr said.

Medics took the victims to Scripps Mercy Hospital for treatment of "major" injuries, Baehr said.

The driver of the Infiniti, a 50-year-old San Diego woman, was transported to UCSD Medical Center, where she was treated for minor injuries and released later in the afternoon.

She told investigators she was reaching for coins in a console inside her car when the crash occurred, according to Baehr.