SANTA CLARITA, Calif. (AP) -- A 15-truck pile-up on a rain-slicked Southern California freeway has left at least 10 injured and the roadway itself compromised.
The intense heat caused concrete to crack and melt, sending chucks falling onto the road below throughout the night. Firefighters worry the damage could cause parts of the tunnel to collapse.
"The tunnel may be structurally compromised, so we're fighting the fire from outside right now," Los Angeles County Deputy Chief John Tripp said.
The crashes left 10 people injured and at least one still missing, as flames shoot out of a tunnel and block a key link between Los Angeles and San Francisco.
Fire Inspector Jason Hurd said the accident -- the wreckage stretching a half mile -- began when two trucks collided late Friday and started a chain reaction in Interstate 5's southbound truck-only tunnels.
At one point flames shot out of the tunnel and 100 feet into the night sky, said Los Angeles County firefighter Scott Clark, one of some 300 firefighters battling the blaze at its height.
"It looked like a bomb went off," said Clark, who battled the flames throughout the night.
The charred skeletons of at least a half-dozen big rigs peek out of the tunnel's south end. At least one truck was carrying produce, and a smoldering load of cabbages lay scattered across the pavement.
By early afternoon, most of the flames appear to have been extinguished, although thick columns of smoke are still curling out of the tunnel and into the surrounding canyons. Firefighters began pouring flame-retardant foam into one end of the tunnel to douse any hot spots.
Twenty people stumbled from the fiery tunnel on foot, including the 10 injured, Hurd said. Five trucks are stuck inside. One truck driver was known to be unaccounted for, but authorities worry more may be missing.
Although the tunnel is designed to carry truck traffic through a mountain pass area, Hurd said passenger cars may also use it. That also raises concerns some may be trapped inside.
"We're going to have to do a very methodical search," Tripp told KABC-TV said. "There could be unfortunately more people that were not able to escape."
Authorities said eight have minor injuries and two have moderate injuries, ranging from moderate burns to neck and back injuries. All 10 injured were taken to local hospitals.
State transportation department engineers are inspecting the tunnel and the freeway above to determine whether firefighters and rescue workers could enter to douse the remaining flames and look for anyone who might have been trapped.
The interstate, a key route connecting Los Angeles to San Francisco, as well as a major commuter link connecting Los Angeles to its northern suburbs, was expected to remain closed throughout the day Saturday and perhaps longer.
"It could be another day, it could be days, it could be weeks," Hurd said.
The freeway is roughly 30 miles northwest of downtown Los Angeles.