"We started to notice really, really thick smoke and strong smell like burning rubber," motorist Kevin Watkins said.
Two-thirds of the way through the Caldecott Tunnel when it started to fill with smoke and people stopped and started jumping out of their cars.
"It was hard to breathe," Watkins said. "I did not have a scarf or anything, but I did put my shirt up over my face. Other people had scarves wrapped around their some people had masks, like dust protector masks."
"Officers and fire department responded to the scene to find a vehicle fully engulfed and the tunnel filled with smoke," California Highway Patrol Ofc. Daniel Hill said. "We calmly cleared everybody out of their vehicles and out of the tunnel."
Eight people were transported to area hospitals to be checked for possible smoke inhalation but there were no serious injuries.
Hundreds of cars were backed up on eastbound Highway 24 for more than 90 minutes before Caltrans was able to remove the burned up car and several others left behind by their owners.