Investigators say speed played a factor in a crash that killed a 22-year-old man Thursday.
A car and a motorcycle collided around 4:10 p.m. on eastbound Interstate 8, just west of Interstate 805, in Mission Valley. Officials say the black Suzuki became trapped underneath the sedan, and a fuel leak caused both vehicles to catch on fire.
Aerial pictures showed smoke swirling above the accident site. Officials say witnesses attempted to put out the fire with hand extinguishers.
The California Highway Patrol issued a Sig Alert. At one point, the entire eastbound side of the freeway was closed. It backed up traffic for miles during rush hour.
Bystanders performed CPR on the motorcyclist, but he was pronounced dead at the scene, according to CHP. His name has not yet been released but the San Diego County Medical Examiner's office has confirmed that the man was an active-duty military servicemember.
The driver of the sedan, a 53-year-old woman from Chula Vista, was visibly shaken but uninjured.
Investigators say the motorcycle was going approximately 100 miles per hour at the moment of impact. The motorcyclist was trying to merge onto southbound I-805 from I-8.
"He came upon slower moving traffic. He was unable to stop in time," CHP Sergeant Jack Mears said.
Mears says motorcycles cutting between lanes of heavy traffic is a common problem on San Diego roads.
"They have to drive safe, just like anyone else," Mears said.
One witness tells NBC 7 that she saw a second motorcycle speed off right after the accident happened.
"It sounded like a bomb coming from the same area where the black motorcycle had just left," Alyssa Ehrlich said.
"Either they were racing or some road rage was going on," Ehrlich said.
So far, the investigation has not indicated anything more than operator error, according to CHP.
"We have no factual basis for any type of racing at this time," Mears said.
Erlich may have been the only witness to observe the second motorcycle because of her place in traffic.
"It's just absurd to think that somebody would just leave that quickly from a scene. Then a half second later, there is another motorcyclist dead in flames," she said.