The search for the cause of the crash continued as the names of more victims, many high school students from the Los Angeles area going on a college tour, were released.
"We're going to look at whether seat belts might have kept them in place and whether that would have made a difference," NTSB board member Mark Rosekind said Saturday.
PHOTOS: Bus crash
So far, eight of the 10 dead have been identified. The Times has produced a profile of each victim.
"We have no one that's missing. All the names are accounted for. We just don't know which body goes with which name," said Larry Jones, sheriff and coroner for Glenn County, north of Sacramento. "And we don't know at this point what body to release to what family."
Dorsey High School student Jennifer Bonilla, among those recently confirmed dead, was a devoted, self-motivated student who had a college scholarship in hand, according to staff members at the Crenshaw-area school.
Teacher Noah Lippe-Klein had recently written a letter of recommendation for the teenager and praised "her ability to think critically about the world and her profound, college-level writing skills."
A member of the campus eco-club who participated in beach cleanups and environment walks in Baldwin Hills, Bonilla had been accepted into a number of schools and was excited about the tour of Humboldt State University tour, Lippe-Klein said.
Ismael Jimenez and Denise Gomez -- friends and students at Animo Inglewood Charter High School -- also were confirmed dead. The two 18-year-olds and a group of other friends had been close since middle school, where they liked to congregate around a favorite oak tree, a friend said.
Jimenez was an honor student who was passionate about art, constantly drawing and painting, his sister Evelin said. He drew pictures for everyone in his life, particularly drawings of horses for his mother and various scenes for his girlfriend of nearly three years. He was "beyond excited" to be bound for college and a career in art, his sister said.
Gomez was a music lover who played the guitar and led the Earth Club at the Inglewood school, according to friend Frankie Martin, another Animo High senior. Martin said the Humboldt State-bound student loved the outdoors and encouraged him to pursue his own college dreams.
Meanwhile, officials were trying to piece together witness accounts of how the crash occurred.
A woman who reported that the FedEx truck sideswiped her car moments before Thursday evening's fatal accident said she saw flames coming from beneath the twin-trailer vehicle as it veered across a grassy median and hit the bus.
However, a man who lives near where the crash occurred on Interstate 5 in Orland, Calif., said he saw no flames from the truck as he watched it swerve out of control after it made an abortive attempt to move into freeway's fast lane.
Both witnesses said the truck veered sharply from southbound lanes, crossed the median and then ran into the Silverado Stages charter bus, which carried 48 people, including 44 Southern California high school students.
"When they collided, it was boom!" said Ryan Householder, 31, who saw the crash as he had been mowing his lawn. He said he was haunted by the screams of those who couldn't escape the burning bus.
The NTSB's Rosekind said Saturday evening that the truck left no skid marks on the roadway or the median. In contrast, more than 145 feet of tire marks indicated that the bus driver tried to stop and swerve to the right, he said.
"That driver was clearly reacting to a situation with braking and a driving maneuver," he said.
Rosekind cautioned that it's too early in the investigation to determine what prompted the FedEx driver to leave the southbound lanes. The investigator said blood samples had been obtained from the drivers, both of whom died in the crash. The samples will be used to test for alcohol, drugs or medication, he said.
Rosekind said a black-box-style electronic device was recovered from the bus and will be analyzed. The truck's device was destroyed, but other steps will be taken to analyze the machinery, he said.
He said the bus was a "very new motor coach" -- only about a month old. The FedEx truck was manufactured in 2007, he said.
Bonnie and Joe Duran, who live near Tacoma, Wash., had just passed the charter bus and were heading north when the FedEx truck suddenly burst across the median, according to the NTSB official.
"It was on fire already," Bonnie Duran, who was driving, said of the truck. She told NBC4-TV that the flames appeared to be coming from the lower rear of the truck cab.
She told the TV station that she tried to veer her rented four-door Nissan Altima to the right, but that it was too late. The FedEx truck sideswiped her, ripping off the rear passenger door. A moment later, the truck slammed into the charter bus, she said.
Neither of the Durans was seriously injured in the incident.
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