Investigators spent all Thursday night and the early hours of Friday morning collecting clues that could potentially lead them to a better understanding of the fiery head-on collision that killed 10 people.
43 students from the Los Angeles area were on the bus, along with three adult chaperones, to take a college tour at Humboldt State.
The bus had one driver, and the FedEx truck had one driver and no passengers. The crash shut down northbound Interstate 5 for nearly 19 hours.
"We don't know whether the FedEx driver had fallen asleep, whether he experienced a mechanical failure, or if there was a separate collision on the southbound side to cause him to lose control,” said Lieutenant Scott Fredrick of the California Highway Patrol.
Nine people were pronounced dead at the scene. One person suffered severe burns and died Friday morning at UC Davis Medical Center.
Five of the deceased were students, three were chaperones, and the two drivers also perished in the accident. Investigators said the bodies were burnt beyond recognition.
Right after the impact, there was a tremendous fire with very high temperatures.
The CHP said there were two people in a white sedan that was in front of the tour bus before the crash. The driver was identified as 53-year-old Bonnie Duran.
“They both sustained minor to moderate injuries,” said Lt. Bruce Carpenter of the California Highway Patrol. “They were both transported to one of the hospitals.”
The Glenn County Sheriff's Office said they will have to conduct cavity searches or DNA samples on the victims to the nature of their bodies.
“That means they [the families] are going have to sit there and wait until that positive ID comes,” said Glenn County Sheriff Larry Jones.
The CHP said it could take up to six months before they fully know what happened Thursday afternoon.
The National Transportation Safety Board is also investigating the accident.