Emergency 911 calls released Thursday by the CHP convey the chaos and confusion in the moments after a FedEx truck collided head-on with a tour bus full of students, killing 10 people and injuring dozens of others.
In one of the calls, from a passenger who had just fled the burning bus, the caller's voice sounds panicked and confused.
"I was in a car accident," the caller begins, crying and gasping for air. "I was on a travel bus and we crashed into a FedEx truck."
"Are you still on the bus or off the bus?" the dispatcher asks, after assuring the person the California Highway Patrol and ambulances were on their way.
"We're off the bus, the bus is on fire!" the caller replies, as cries and screams from other passengers are heard in the background.
"Go as far away as you can safely get," the dispatcher advises.
In the few minutes after the crash, as students were kicking out windows to escape the fiery wreckage, there seemed to be some confusion about what had happened and where the collision had taken place.
Multiple callers reported seeing and hearing "a bus explode" and flames coming from the vehicles.
"We have massive fire. We have all kinds of students out here on the highway right now," said one man who called to report the incident. "I just saw the FedEx truck go across the median and crash."
The calls were released as CHP officials began a series of tests to determine the cause of the crash, conducting simulations with vehicles identical to the tour bus and FedEx truck in the April 10 collision.
Morrison said both vehicles had black box-like data recorders on board, but they were badly burned.
"I'm not sure we're going to be able to retrieve the data we need," Morrison said.
Investigators planned to drive the camera-equipped vehicles along a stretch of I-5 near the scene of the accident in an effort to determine what each driver saw as they approached each other, and would also conduct speed, skid, and brake tests, said CHP Capt. Todd Morrison during a news conference Thursday.
Authorities will examine cellphone records of both drivers, maintenance logs, driving records, and any possible recalls of vehicle parts, in the hope of explaining why the FedEx truck barreled across the median and hit the bus carrying Southern California high school students en route to Humboldt State for a college visit.
Both drivers were killed, along with five students and three adult chaperons. Dozens more were taken to hospitals with injuries. All had been released by Wednesday afternoon.
Many families mourned the victims this week, with candlelight vigils across Southern California.
Glenn County Sheriff-Coroner Larry Jones said most of the 10 victims had to be identified using dental records. As of Thursday afternoon, two had yet to be positively identified.
Among the victims most recently confirmed Wednesday and Thursday were Jennifer Bonilla, a 17-year-old student at Dorsey High School; Denise Gomez, an 18-year-old senior at Animo Charter High School in Inglewood; and Marisa Serrato, 17, of Riverside, a student at Norte Vista High School.
Coroner's investigators have not determined a cause of death, Jones said, and results of toxicology reports ordered for all the bodies could take weeks to come in.
It will probably take much longer for officials with the CHP and National Transportation Safety Board to determine what caused the crash.
"We do not speculate on the cause of the collision until we have reviewed all the facts," said CHP Northern Division Chief Ruben Leal. "We owe to the families of the involved parties and the victims of this tragic collision that we tell the story of what happened, and that we tell it as accurately as possible."
Morrison said both companies were being "extremely cooperative" in the probe.
Officials with the CHP and National Transportation Safety Board, who are conducting "parallel" investigations into the incident, said it could be months before a cause is determined.