Five trucks engulfed in flames in tunnel

A 15-truck pile-up on a rain-slicked southern California freeway left 10 people injured, at least one missing and severed a key transit link between Los Angeles and San Francisco, authorities said.

Fire Inspector Jason Hurd said the accident - the wreckage stretching a half mile (800 kilometres) - began when two trucks collided late Friday and started a chain reaction in Interstate 5's southbound truck-only tunnels.

Flames shot out of both ends of the tunnels, which run under the regular freeway near the intersection with the Antelope Valley Freeway, according to broadcast news reports.

"Flames were leaping out of both sides of the tunnel 60 and 70 feet (18 and 21 meters) high," Hurd said.

Twenty people evacuated the fiery tunnel on foot, including the 10 injured, Hurd said, and five trucks were stuck inside. One truck driver was unaccounted for, and authorities were worried that 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, raising concerns that some may be trapped inside.

"We're going to have to do a very methodical search," Deputy Chief John Tripp told KABC-TV said. "There could be unfortunately more people that were not able to escape."

Authorities said eight had minor injuries and two had moderate injuries, ranging from moderate burns to neck and back injuries. All 10 injured were taken to local hospitals.

The intense heat caused concrete to crack and melt, sending chucks falling on to the road below throughout the night. Firefighters worried that 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," Tripp said.

State transportation department engineers were 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 today and perhaps longer.

The freeway is roughly 30 miles (50 kilometres) north west of downtown Los Angeles.