(AP) SANTA CLARITA Nine drivers believed to have escaped a deadly tunnel inferno are unaccounted for, and authorities on Monday were scrambling to locate them.

Thirty-one vehicles were involved in the pileup in the curving, darkened tunnel on Interstate 5, but the California Highway Patrol has accounted for only 23 people, including two men and a 6-year-old boy who died in the fire.

If all of them were at the wheel at the time of the crash, excluding the boy, that leaves nine unaccounted for drivers. The number could be higher if there were passengers.

Investigators are confident only three people died, but CHP Assistant Chief Warren Stanley said it's a mystery what happened to the others who left their vehicles to the flames.

"We have no idea," Stanley said. "We haven't identified all the vehicles, we haven't identified all the drivers."

As the highway reopened early Monday, investigators worked to identify vehicles, some of which were reduced to molten steel in the fire's intense heat. They were also trying to locate drivers, passengers and any witnesses to the accident.

Authorities said 10 people were hospitalized with minor or moderate injuries from the fiery crash Friday night. Another 10 people escaped the flaming tunnel unscathed.

As of Monday, the CHP had received no missing person reports connected to the crash. Stanley said investigators expanded their search, including contacting local agencies to find people involved.

It is unclear where the drivers disappeared to as the tunnel sits under the interstate, nestled in mountain canyons.

Investigators haven't figured out what caused the pileup inside the 550-foot long tunnel three days after the crash.

State Transportation Department district director Doug Failing said officials were trying to determine the extent of the damage to the steel and concrete tunnel. The fire burned so intensely that it melted concrete and caused reinforced steel bars to pull away from the concrete.

State transit officials have since installed supports to buttress the tunnel's roof.

Signs of the accident's magnitude were everywhere outside the tunnel - from the blackened, blistered walls to the smashed cantaloupes and dented cans that lay against a pillar where a produce truck smashed into it just outside the tunnel. Thousands of nails littered the ground, remnants of another truck that lost its cargo in the accident, Failing said.

During a tour of the inside of the tunnel, Failing showed an AP reporter places where extreme heat from burning vehicles melted holes two to three inches deep into the ground and walls, exposing reinforced steel bars used to support the tunnel.

Deep grooves were burned into the ground and along the walls - a path burned by gasoline that leaked from vehicles and ran down the tunnel's gentle incline, pooling against the walls.

Wind tore through the tunnel, still black with soot. Failing said it was the wind blowing through one entrance of the tunnel that stoked the fire, which moved from vehicle to vehicle.

"We know there is damage. We are not sure how deep into the cement it goes," Failing said.

There is no schedule for reopening the damaged tunnel.

Traffic, meanwhile, moved smoothly during rush hour after transportation officials reopened all main lanes of the interstate. The fire-damaged tunnel, which routes trucks beneath the highway on a grade down Newhall Pass, will be closed indefinitely.

The reopening of Interstate 5 came quicker than expected after officials initially said the freeway might remain shut for days. California Highway Patrol spokesman John Lutz credited state road crews for working nonstop to reopen the freeway.

Investigators have determined that 31 vehicles - including big rigs and one passenger vehicle - were involved in the crash 30 miles north of Los Angeles.

The driver of the passenger vehicle is among those who escaped, Stanley said.

Investigators are waiting for dental records to help identify the dead, who were burned beyond recognition, Los Angeles County Coroner's Lt. Cheryl MacWillie said.

Two of the victims, believed to be a 38-year-old man and a 6-year-old boy, were riding together in a big rig, MacWillie said. Officials previously said the child in the truck was an infant.

The third body found in a truck is believed to be Ricardo Cibrian, said Espree Campos, a family friend. She said authorities notified the family Saturday they found a body in Cibrian's truck in the tunnel.

Cibrian's wife, Victoria Martinez, and Campos's mother left Monday for Tijuana, Mexico, to retrieve Cibrian's dental records from his dentist "so they could identify his body," said Campos, 21.

Martinez, a housekeeper, last heard from her husband on Friday night around 9 p.m., when he called saying he was on his way home, Campos said.

About two hours later, Cibrian was on the phone with a friend, who heard an explosion, Campos said.

Cibrian had been working as a truck driver the past six or seven years and hauled everything from food to clothing, Campos said.

Truckers use I-5, the main West Coast interstate linking Mexico and Canada, to haul produce from the Central Valley to Southern California and to move goods north from the ports of Los Angeles and Long Beach. It is also a major route from Los Angeles to northern suburbs.

Gov. Arnold Schwarzenegger declared a state of emergency in Los Angeles County, which will allow the state to deploy emergency workers and equipment and give aid to local government.

The 1970s-built tunnel has long been regarded by truckers as one of the most dangerous areas of the freeway. State transit authorities said the tunnel was safe as long as drivers were careful.

(© 2007 The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. )

At least nine drivers who apparently escaped from vehicles trapped in the burning truck bypass tunnel in the Newhall Pass had not yet contacted the Highway Patrol, officials said.

One team of CHP specialists was working to identify the missing drivers as well as passengers and witnesses. Another team is working to identify the commercial vehicles - some of them burned to charred metal frames - through the trucking companies.

Posted By: Rayelan
Date: Tuesday, 16 October 2007, 1:15 p.m.

RMN - 10.16.07 -- Nine drivers, whose trucks were involved in the fiery chain reaction crash, in a special truck-only tunnel on California's Interstate 5, are missing.

Over 30 vehicles, mostly trucks were involved in the crash. 3 were killed, two men and one six year old boy. Everyone is accounted for except 9 drivers who were seen exiting the tunnel.

Why did these drivers disappear?