A day after a collision involving a bus carrying high school students and a FedEx truck left 10 people dead, officials began to identify the victims as investigators tried to determine what went wrong on the Northern California highway -- a process that will likely take more than three months.
California Highway Patrol officials and other public safety personnel said at a news conference Friday morning that nine people died at the scene of Thursday's crash and a 10th victim died at a hospital. Those killed included five students and five adults who were traveling to Humboldt State University for a campus visit.
Thirty-one victims were hospitalized after the crash. Their injuries ranged from critical to minor, CHP officials said.
The bus was one of three transporting students to the Humboldt campus, and authorities said they are examining "all vehicles involved" in the crash. A car -- described as a Nissan Altima -- also was struck, but authorities are attempting to confirm details about the vehicle's involvement in the collision.
The two occupants of the sedan suffered minor to moderate injuries, according to the CHP.
It remained "unclear" whether the FedEx driver fell asleep or experienced a mechanical failure on the vehicle, CHP officers said Friday.
The side windows of the tour bus would not open as passengers tried to break out; the rear windows did open, investigators said.
A final report on the crash might take up to six months, according to the CHP.
"Since these are such in-depth, detailed investigations, we don't expect to have a final report for a minimum of three months, 90 days," said CHP Lt. Scott Fredrick. "It could take as long as six months depending on what the investigation entails."
The update comes as coroner's officials confirmed the identity of a crash victim -- 26-year-old Arthur Arzola, a Humboldt State University admissions counselor based in Los Angeles. He was described as a counselor with a "passionate commitment to helping low-income and first-generation students get into college."
Another crash victim was identified by family members Friday as 18-year-old Adrian Castro, a student at El Monte Union High School. Two other students from the high school who were on another bus were hospitalized.
A mother who spent 24 hours after the crash wondering whether her daughter survived confirmed Friday night the twin teen, Marisa Serrato, died in the crash.
Two chaperones, a newly engaged couple, also died in the fiery bus wreck.
"These are lives lost just as they were beginning to be transformed," said Los Angeles Mayor Eric Garcetti at a mid-day news conference.
Sheriff's officials said they will rely on dental records and DNA tests to determine some of the victims' identities because of severe burns suffered in what passengers described as a ball of fire that raced through the bus.
The burned wreckage of the tour bus remained at the crash site Friday morning on Interstate 5 near Orland, about 90 miles north of Sacramento. About 40 passengers -- including 19 Los Angeles Unified School District students -- were on the bus when a FedEx tractor-trailer veered across a grassy highway median and slammed into their bus in a fiery wreck, authorities said.
Passengers described a "surreal" scene as people kicked out bus windows to escape the fire and smoke after the crash.
"I looked forward to the bus and I just see fire," said student Karmin Aguilar. "Just fire, a ball of fire."
Two other buses that were part of the campus trip were not involved in the crash.
An autopsy will determine whether the driver of the FedEx truck had a medical condition or was deceased before the accident. The bus belonged to Silverado Stages, a tour bus company based out of San Luis Obispo.
Silverado Stages is one of the largest charter bus companies in California. It has a good safety record, though the company had two crashes in the last three months, according to Federal Motor Carrier Safety Administration records.
FedEx, however, has been involved in 171 accidents in California -- five of them fatal -- in the last two years, according to safety records.
A FedEx spokesperson confirmed Friday that the vehicle involved was a freight tractor pulling two trailers. The truck is company owned and operated, the spokesperson told NBC4.
The National Transportation Safety Board sent a team to investigate.
"Every piece of paper associated with this will be looked at," said Eric M. Weiss, an NTSB spokesman.