Authorities in California were trying to determine Friday how a joyous university recruiting trip for low-income high schoolers turned into a fiery tragedy on a Northern California freeway.
A spokesman for the California Highway Patrol said it could take months to determine why a FedEx tractor-trailer roared across a narrow, brushy median of Interstate 5 about 5:40 p.m. PT Thursday, slamming into a charter bus and sparking an inferno that left 10 people dead and dozens more injured.
The dead included a Los Angles couple who were engaged recently in Paris, family members said. A 17-year-old girl whose twin sister was aboard a different bus is also feared dead.
The truck inexplicably veered across the two lanes of southbound I-5 and plowed through oleander bushes planted along the divide, said Officer Matt Thompson. The 2007 Volvo cab then sideswiped a northbound 2013 Nissan Altima in the passing lane before hitting the brand-new coach, which was behind it in the slow lane.
Many of the 43 students on board escaped through a window one of them had kicked open, running from the wreckage before the bus exploded behind them near the town of Orland, about 100 miles north of Sacramento.
The bus passengers were mostly high school seniors on their way to visit the campus of Humboldt State University in Arcata, Calif. The crash killed five students, their three chaperones and the drivers of both vehicles. The CHP said that 34 passengers suffered minor-to-major injuries.
The driver of the car -- Bonnie Jean Duran, 53, of Lake Tapps, Wash., near Seattle --and her passenger suffered minor injuries, the CHP said.
Investigators were breaking down possible causes for the crash, including whether the FedEx driver fell asleep, suffered a medical emergency, was distracted by a cellphone or something else, experienced mechanical failure or lost control because of the collision with Duran's car.
Authorities also will probe roadway and weather conditions.
"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."
Because of the impact and the intense fire, DNA and dental records may be needed to identify the truck and bus drivers and some other victims, and their names might not be confirmed until next week, the CHP's Thompson said.
A Glenn County coroner's official said Friday that autopsies were being conducted and that positive identifications might take "a couple of days, maybe less."
The Los Angeles Timespublished the names of the confirmed dead and those not yet identified.
The Sacramento County coroner's office on Thursday confirmed the name of one victim — Arthur Arzola, 26, of Rancho Cucamonga.
Humboldt State spokesman Frank Whitlatch said Arzola was an admissions office staff member who was with the students on the bus when it crashed. He had been the school's admission representative in Southern California for the past year, focusing on recruiting low-income and first-generation students — the ones invited to the weekend "Preview Plus'' event on campus. He was a 2006 graduate of Don Lugo High School in Chico, Calif.
In his online bio, Arzola mentions that he liked to walk on the beach when he visited Humboldt. It was a major recruiting factor for him; Whitlatch said that the campus' location usually ensured that students who visit it want to attend it.
The National Transportation Safety Board sent an investigative "go team" from Washington to the scene. The agency said NTSB Highway Safety Investigator Robert Accetta was leading a "multi-disciplinary" team. The highway patrol is leading the probe.
A 13-mile stretch of northbound I-5 that had been closed was reopened early Friday afternoon.
The investigation is focused on the FedEx truck. FedEx Freight Inc. has a satisfactory safety rating, according to Federal Motor Carrier Safety Administration records. FedEx Freight has a 0.7% unsafe driving on-road record — one of the best scores for companies of its size that perform the same operations, according to FMCSA.
During the two-year period that ended Thursday, the company's vehicles were involved in 730 crashes in the USA. Twenty-three of those were fatal crashes, 223 were injury crashes, and 484 were tow-away crashes.
FMCSA's website simply lists a motor carrier's involvement in reportable crashes with no determination as to responsibility.
FedEx would not comment on any aspect of its safety record beyond a brief statement posted on its website. "All of us at FedEx are deeply saddened by the tragic highway accident in California. Our hearts go out to all of those involved and their families. We are cooperating fully with the officials investigating this accident."
In a statement Friday, FedEx CEO and Chairman Frederick Smith expressed his "deepest personal sympathies and the condolences of over 300,000 other FedEx team members to everyone involved in this accident."
He said it would "take some time to fully understand exactly how this accident occurred and why. In the meantime, I want everyone to know that we at FedEx are committed to providing every resource necessary to assist investigators in their efforts to understand what happened."
The bus company involved in the crash, Silverado Stages, of San Luis Obispo, Calif., also has a satisfactory safety rating. It was involved in one injury crash and one crash requiring a tow truck in the two years prior to Thursday, according to FMCSA.
The bus company said Friday that it is "helping the authorities in gathering information regarding the tragic accident. .. Our top priority is making sure that the injured are being cared for. Our thoughts and prayers are with the injured, their families and everyone affected by this accident."
Humboldt State issued a statement saying it was "deeply saddened, adding, "Our hearts go out to those who have been affected, and we are here to support them, and their families, in any way possible."
The bus was one of three the university had chartered for a two-day spring preview for prospective students from Southern California and the San Francisco Bay Area to tour the campus. The other two buses arrived about two hours before the crash, and students were being offered counseling.
Students from 37 Southern California high schools were aboard the bus that crashed. Tommy Chang, the instructional superintendent for the Los Angeles School District, confirmed that 19 students from Los Angeles schools were involved in the wreck, but he declined to provide further details.
The trip gave the students "an amazing opportunity to see what this amazing state has to offer in terms of higher education," Chang said.
Contributing: William M. Welch; William Cummings; The Associated Press