SAN DIEGO -- A car traveling at freeway speed struck and killed a 24-year-old emergency medical technician Thursday as he was laying out flares around vehicles that had crashed amid rain and rush-hour traffic on the Cabrillo Freeway in Hillcrest.

Esteban Bahena of Lemon Grove, an employee of San Diego Medical Services, died at Scripps Mercy Hospital about 8:30 a.m., roughly 90 minutes after the accident, authorities reported.

Bahena and a colleague were northbound in an ambulance on the freeway during a cloudburst about 7 a.m. when they came across the aftermath of two separate crashes that had just occurred near Washington Street, according to the California Highway Patrol.

After he and his partner checked on the occupants of the vehicles that had been involved in the accidents, Bahena began placing flares on the wet roadway to warn oncoming motorists, CHP public affairs Officer Art Athans said.

Within moments, a silver 2001 Chrysler Sebring struck Bahena, then hit two of the disabled vehicles.

A short time later, a San Diego Fire-Rescue Department vehicle happened upon the scene, and its crew performed CPR on the medical technician. Medics then took him to the nearby trauma center, SDFRD spokesman Maurice Luque said.

The 55-year-old San Diego woman whose car hit Bahena was taken to USCD Medical Center for treatment of undisclosed injuries, Athans said. At her request, blood samples were taken to test for any possible intoxicants in her body, and the screening determined that she was not under the influence of drugs or alcohol, according to Luque.

The CHP closed the northbound lanes of the freeway between Interstate 5 and Washington Street until about 3:30 p.m. to allow investigators to gather evidence and document the scene of the deadly accident.

The fatality was the first on-duty death in the 13-year history of San Diego Medical Services, a public-private partnership between the city and a national emergency-services company. Bahena had worked for the agency since August 2008.

Philip Forgione, chief executive officer of SDMS, described the organization's personnel as "stunned and devastated."

"Our paramedics and EMTs serve the San Diego community every day, and Esteban was one of our very well-liked and exemplary employees," Forgione said.

Bahena's death was the eighth on-duty fatality in the history of the city's fire department, according to Luque. The most recent one before Thursday's occurred in 1976, he said.