SPARKS, Nev. -- Authorities say five people remained unaccounted for following a fiery crash involving a big rig and an Amtrak train in the Nevada desert, but investigators say they've yet to find any more bodies in the wreck that left six dead.
Amtrak lowered the number of unaccounted passengers Sunday, a day after authorities said they couldn't locate 28 of the more than 200 passengers believed to be on board at the time of the collision Friday. The company also said 14 crew members were on the California Zephyr from Chicago.
Churchill County coroner officials sifted through the rubble of two rail cars gutted by the fire that sparked after the truck slammed into the side of the train. Investigators said they have found no additional victims.
The blaze was so hot that authorities "want to make sure they are not missing anything," so the coroner's office has asked at least one forensic anthropologist to help, Nevada Highway Patrol Trooper Chuck Allen said.
"They want to figure out if there are any more bodies and if so, how many," Allen said. "They want to rule out the possibility that, yes there are more, or that no, there are not."
Earl Weener, a National Transportation Safety Board member, has said there were unaccounted passengers because some of them may have gotten off the train before the crash or walked away from the scene without checking with officials. Unlike airplane travel with seat records, "on a train, you can get off without necessarily being tracked," he said.
The driver of the truck, a conductor and four others on the train were killed when the semi-trailer truck plowed into the California Zephyr at a highway crossing about 70 miles east of Reno. The big rig, the lead in a three-truck convoy, skidded about 320 feet before smashing through the crossing gates.
Investigators looked for clues as to why the driver failed to stop before the crossing, which had its gates down and warning lights on. Weener said examining the truck tractor has been difficult because part of it was stuck in a rail car.
Weener said that the flashing lights at the crossing, which were set to blink for 25 seconds before a train approaches, would have been visible from a half-mile away if a motorist was driving at the highway's 70-mph speed limit.
Toxicology and autopsy results of the driver were due within days. Allen said authorities would consider "not necessarily just drugs or alcohol, but fatigue, driver inattention."
"Did he have a (citizen band radio)? Was he talking to his buddies behind him? If so, was he looking in the side-view mirror and not looking at the road ahead? I don't think we'll ever know for sure," Allen said.
"Just from handling or being on the scene of so many accidents, there are so many alternatives to consider," he added. It's expected to take up to a year to pinpoint the cause of the crash.
The driver was working for John Davis Trucking Co. in Battle Mountain, Nev. Its website said it was family owned and specialized in hauling ore from local mines, as well as moving gravel and sand. The company did not immediately return a call or email Sunday.
Federal records reviewed by The Associated Press showed the Nevada Department of Public Safety has cited the company for crashes, unsafe driving, and most seriously, operating a truck with tire treads so exposed that it had to be taken off the road.
In that January inspection, authorities deemed the rig an imminent hazard to public safety. The company was also cited for two crashes in the last two years, including one in February 2010 that injured a person in Washoe County. Federal records do not detail who was at fault.
Weener said the company had received seven violations since 2010 and that one of them forced a truck to be taken out of service, but he provided no other details. It was difficult to say whether the company's record was significant or atypical in the industry, he added.
The federal records showed the other citations were for issues such as oil leaks and inoperative lamps, a company driver who didn't use a seat belt, and lane restriction and cargo violations. They were not deemed sufficiently serious to order the vehicle off the road.
Allen said it was not unusual for state public safety officials conducting spot roadside inspections to take trucks out of service for unsafe driving practices or discrepancies in travel logs.
He said he wasn't familiar with the trucking company's record but that "having just a couple of tickets, I don't think is an alarming issue."
Weener said investigators would meet with the company Tuesday and review the driver's medical history, training and experience. He also has said the driver's professional commercial driving record "is an area we will be taking a very close look at."
More than two days after the accident, a variety of factors remained unknown, including how fast the driver might have been going, Weener said.
Two other truck drivers in the convoy and the train's engineer watched the semitrailer skid the length of a football field before crashing into the train. The other drivers stopped when they saw the gates come down and the warning lights go off as the California Zephyr approached, Weener said. The driver of the big rig in the lead did not.
The train's engineer slammed on the emergency brakes, but the train, which was going about 78 mph in an 80-mph zone, traveled a half-mile more before it finally stopped, Weener said. The man watched "the collision in a rearview mirror. He was hoping the train was not going to derail."