Authorities have begun releasing the names of the 10 people killed when a FedEx truck slammed into a charter bus Thursday evening near Orland. Dozens more were injured.
The California Highway Patrol said the 10 who died were the driver of the FedEx semi, the bus driver, five students and all three chaperones.
Among the victims was chaperone Arthur Arzola, 26, of Rancho Cucamonga. He was a recruiter for Humboldt State University.
The Associated Press said Debra Loyd, the grandmother of Michael Myvett, confirmed Myvett and his fiancee, Mattison Haywood, were killed in the crash. Myvett and Haywood were the other two chaperones and had just become engaged in December.
Officials said they were still working to identify others who died.
A total of 48 people were on the bus. The passengers were high school seniors and their chaperones on their way to visit the campus of Humboldt State University.
Nine people were pronounced dead at the scene. Another person suffered major burns and later died at the University of California, Davis Medical Center. An additional 34 people were injured, according to the CHP.
The CHP is working with the National Transportation Safety Board (NTSB) on the investigation.
CHP officials said they will be looking at vehicle mechanical issues, road conditions and the crash histories of FedEx and the charter bus company as they try and determine why the FedEx truck roared across the median of Interstate 5 and slammed into the bus, causing a fiery explosion.
An NTSB investigative team arrived Friday. A spokesperson said they will also be investigating whether human and environmental factors contributed as well as if other vehicles played a part. The have to learn if blood samples were taken from the drivers, as is standard practice in deadly crashes and whether seatbelts or the lack of them played a role in survival.
The CHP said it could take up to six months to determine what happened.
Crash victims were taken to seven local hospitals.
Enloe Medical Center in Chico received 11 patients. As of late Friday afternoon, hospital spokesperson Christina Chavira said eight had been discharged and three remained in fair condition.
University of California, Davis Medical Center officials said a female victim was in critical condition at their facility.
Nineteen of the passengers were students who attended schools in the Los Angeles Unified School District. California State University Chancellor Timothy White said many of the students were from low-income homes and they hoped to be the first in their families to attend college.
The crash was a tragic event "of a magnitude not typical to this county," CHP Northern Division Chief Ruben Leal said. Most of the deceased victims were found in the front of the bus, and the impact of the crash could be heard throughout much of Orland, CHP officials said.
The Red Cross responded and was working with victims' families at a local veterans' memorial hall. Red Cross spokesman Jordan Scott said that the agency was not in need of donations for its relief efforts.
He asked people to keep the victims' families in their thoughts and prayers.
Many of the students on board escaped through a window one of them had kicked open, running from the wreckage before the bus exploded behind them. One emergency responder said they were treating for injuries such as burns, broken bones and cuts.
"The victims were teenage kids. A lot of them were freaked out. They were shocked. They still couldn't grasp what happened," said Jason Wyman with the Orland Volunteer Fire Department.
Steven Clavijo, 18, a student at West Ranch High School in Santa Clarita, said he was on the bus during the crash.
Clavijo said he was just getting ready to fall asleep in the back of the bus when he felt the vehicle begin to swerve.
"I just heard this loud boom," he said. "We knew we were in major trouble."
FedEx Freight Inc. has a satisfactory safety rating, according to Federal Motor Carrier Safety Administration records. FedEx Freight has a 0.7 percent unsafe driving on-road record -- one of the best scores for companies of their 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 U.S. 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.
Friday afternoon, FedEx Chairman and CEO Frederick Smith issued this statement:
Like so many of you, I have watched with great sadness the reports of the tragic accident involving a FedEx Freight vehicle and a tour bus in Northern California.
First and foremost, I want to express my deepest personal sympathies and the condolences of over 300,000 other FedEx team members to everyone involved in this accident, including the families of the students and others who lost their lives and those who were injured and the families and friends of the FedEx Freight driver who died in the crash.
It will 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.
Just as important, we are committed to providing support for our team members, their families and the families of all of those who lost their lives. This is a tragic day for these families, and our thoughts and prayers are with them.
The bus company involved in the crash, Silverado Stages of San Luis Obispo, 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.
USA TODAY contributed to this story