ORLAND, CA - APRIL 11: The remains of a FedEx truck, right, and bus, left, involved in Thursday's deadly crash are seen on trucks at the scene of the accident on April 11, 2014 in Orland, California. Ten people were killed and dozens injured, including four still in critical condition, after a FedEx truck collided with a bus of high school students on Interstate 5 yesterday. The students were on their way to visit Humboldt State University in Northern California. (Photo by Elijah Nouvelage/Getty Images)2014 Getty Images
This undated photo provided by Humboldt State University shows Arthur Arzola. Arzola, 26, of Rancho Cucamonga, Calif. Arzola, a staff member in the admissions office at Humboldt State who was accompanying students on a visit to the campus, died in the fiery collision of a tour bus and FedEx truck on Interstate 5 near Orland, Calif., Thursday, April 10, 2014, according to the Sacramento County coroner. (AP Photo/Humboldt State University)HUMBOLDT STATE UNIVERSITY_2013
This undated photo provided by El Monte High School football coach Joel Sanchez shows El Monte senior Adrian Castro. Castro died in the fiery crash between a FedEx truck and a chartered bus taking Southern California high school students to Humboldt State University on Thursday, Feb. 10, 2014. Adrian's father, Raul Castro, said he had gotten a call from Adrian's mother, who had heard from the California Highway Patrol that their son had died. (AP Photo/El Monte High School)AP2014
This 2013 photo provided by Miguel Serrato shows twin sisters Marisol Serrato, 17, left, and Marisa Serrato, right, with their sister-in-law Ivette Serrato during a wedding in Riverside, Caif. The twins were part of the group more than 40 high school students whose trip to visit a college turned tragic when a FedEx tractor-trailer veered across a grassy highway median and slammed into their bus in a wreck that left 10 people dead, authorities said. Marisa was one of the twins on the bus that crashed but is still unaccounted for. Marisol was on another bus that wasn't in the accident. (AP Photo/Courtesy Miguel Serrato)
A witness to a fiery crash Thursday that killed students and others who were on a bus that was headed to a college for a tour told investigators and a KNBC-TV reporter that flames were coming from the lower rear of the truck cab involved in the accident.
The truck, a FedEx tractor-trailer, careened out-of-control across a freeway median and slammed into the bus, killing 10 people.
The investigators are looking for more witnesses who could corroborate the driver's claim, and planned to examine crash scene evidence for clues of a fire before the vehicles exploded into towering flames on a Northern California highway, National Transportation Safety Board member Mark Rosekind said Saturday.
He said the truck left no skid marks, on either the roadway or the median, as it veered into oncoming traffic, sideswiping a Nissan Altima before crashing into the bus. Five students, three adult chaperones and both drivers died in Thursday's collision on a stretch of Interstate 5 in Orland, a small city about 100 miles north of Sacramento.
Some of the victims were thrown from the bus, Rosekind said.
"It was in flames as it came through the median," said Bonnie Duran, the witness who was in the sedan. "It wasn't like the whole thing was engulfed. It was coming up wrapping around him."
Initial reports by police made no mention of a fire before the crash.
The bus was gutted and the truck was a mangled mess after the fiery crash, making it difficult for investigators to determine whether a fire started in the truck before impact. Rosekind said investigators planned to look at blood tests to determine whether the FedEx driver inhaled smoke before the collision, and whether he was impaired.
A family member told the Sacramento Bee the truck driver was Tim Evans, 32, of Elk Grove, Calif.
A blood test will also be conducted for the bus driver, who had only been driving a short time after relieving another driver during a stop in Sacramento. Rosekind said more than 145 feet of tire marks showed that the bus driver tried to brake and swerve to the right to avoid being hit.
He said the bus' black box-style electronic control module was recovered and will be analyzed. The truck's device was destroyed, but other steps will be taken to analyze its speed and maneuvering.
In addition to the cause of the crash, federal transportation authorities are examining whether fire safety measures they previously recommended for motor coaches could have allowed more of the 48 bus occupants to escape unharmed.
Bodies recovered from the bus were charred beyond recognition. Dozens of students had injuries including burns, and several remained hospitalized.
Fire safety has been a longstanding concern of the NTSB.
After a 2005 bus fire killed 23 nursing home evacuees escaping Hurricane Rita in Texas, the agency called for safety standards that could make buses less vulnerable to fire, including improved protection of fuel tanks. More recently, the NTSB says buses must have sophisticated suppression systems to control fires, much as high-rise buildings have sprinkler systems.
The NTSB, which investigates accidents and their causes, has no authority to require safety changes it recommends.
But a bill passed by Congress in June 2012 directed the Department of Transportation to conduct research and tests on ways to prevent fires or mitigate the effects, among other safety issues. That included evacuating passengers, as well automatic fire suppression, smoke suppression and improved fire extinguishers. Representatives of the bus industry told Congress that manufacturers were increasingly and voluntarily adding such features.
As part of its investigation into Thursday's crash, the NTSB will also evaluate whether there should have been a barrier on the median to help prevent head-on collisions. Barriers are required when medians are less than 50 feet wide; this one was 60.
The 44 Southern California high school students on the bus, many hoping to become the first in their families to attend college, were on a free trip arranged by Humboldt State University. The university chartered two more buses to bring more than 500 prospective students to the campus for a three-day visit. Those who made it to the university were sent home earlier than scheduled Saturday morning in light of the tragedy.
Meanwhile, five high school students and three chaperones who were on the bus have been confirmed dead or are unaccounted . Below is information about some of them.
Michael Myvett had spent years connecting to autistic children as a therapist, and now was playing chaperone to a different group of youth as he traveled from his Southern California home to Humboldt State, his alma mater.
He was also a proud groom-to-be, traveling with Mattison Haywood, the fiancee he proposed to in Paris at Christmas.
The couple would make it neither to the school nor their wedding, dying in a fiery highway crash instead.
"He was my grandson, the greatest grandson any grandparent could ever have," Myvett's grandmother Debra Loyd told The Associated Press through tears.
Myvett had worked at the Center for Autism and Related Disorders in Torrance for two years.
Operations manager Kyle Farris, one of Myvett's supervisors, said he and another therapist heard about the couple's death on Facebook on Friday morning and were very broken up by the news.
Farris described Myvett, a Humboldt State alumnus, as "a child at heart" who loved comic books and video games, fantasized about working as a Disney cartoonist and bonded with his young clients by drawing cartoon characters for them.
"He wanted to help people succeed, and to be a liaison and representative for high school students who wanted to attend Humboldt was in sync with his personality, wanting to facilitate people's achievement of their dreams," Farris said.
Myvett proposed to Haywood outside the Louvre Museum in December. Facebook photos posted by the beaming couple show Haywood teetering on the platform pumps Myvett had asked her to wear while he extended a ring on bended knee.
"That was the love of his life," Farris said.
Separated by five minutes at birth and a waiting list as they approached college, 17-year-old identical twins Marisol and Marisa Serrato of Norte Vista High School in Riverside, Calif., found opposite fates as they got on different buses headed for Humboldt.
Marisol, who'd been accepted to the school, arrived without incident Thursday.
There was no word on Marisa, her "baby" sister who was on the school's wait list, for nearly 24 hours before dental records confirmed she was among the dead.
Miguel Serrato said Marisol called their father Friday evening after going to see her sister's body.
"Marisol is devastated," the tearful brother said.
Arthur Arzola, who made it to a hospital burn unit before he was declared dead, was a Humboldt State admissions counselor and newlywed also acting as a chaperone on the trip.
From the wide grin he wears on his bio on the school website while clad in Humboldt's tree-green and the love he expresses for the town's restaurants, you wouldn't know he actually lived and worked 600 miles away, where he sold Southern Californians on the pleasures of going to school in the far north of the state.
A university statement praised Arzola for his passionate commitment to helping low-income and first-generation students get into college.
The University of LaVerne in Southern California said Arzola was a graduate student in educational counseling who had recently married a LaVerne alumna and was set to receive his degree in May.
"Arthur has been described by his colleagues as one with a passion and commitment in helping students reach their academic dreams," University of La Verne President Devorah Lieberman said.
A senior football player at El Monte High School east of Los Angeles, Adrian Castro was considering going to a California state university nearer to home but decided to give faraway Humboldt a chance and a visit.
"He told me two days ago: 'Should I go up and check it out anyway?'" said father Raul Castro, who would see his son for the last time when he dropped him off for the trip Thursday morning.
Later that night, he got a call from Adrian's mother, who had heard from the California Highway Patrol that he had died.
"Adrian Castro will be missed as a student and football player," El Monte football coach Joel Sanchez told the San Gabriel Valley Tribune. "He was a good young man with a bright future. He will always be remembered by the El Monte family."
Jennifer Bonilla was the model student.
"She's one of those students who is bright and shiny and eager and ready to go," Sherlett Hendy Newbill, a teacher at Dorsey High School, told the Los Angeles Times.
Friends said Bonilla was on the bus that crashed. She remained unaccounted for after the crash.
Classmate Melvin Harris, who was asleep when the collision occurred, broke a window to jump out.
"I looked back and I saw a whole bunch of other kids breaking windows and falling on top of each other trying to get out, and I was also trying to look for my friend," he told KCAL-TV in Los Angeles.
Teacher Noah Lippe-Klein told the Times he recently wrote a letter of recommendation for a scholarship that Bonilla won.
He admired Bonilla's "ability to think critically about the world and her profound, college-level writing skills."
Denise Gomez, who played soccer at Animo Inglewood Charter High School, was among the students who remained missing.
"Great kid, sharp, energetic," Gomez's former soccer coach, Roger Flores, told KCAL-TV. "Always smiling and a little quiet, but she was a happy child. I just know she was looking forward to go out and do her college trips."
Ismael Jimenez, a classmate of Gomez's, was an 18-year-old honor student who was "beyond excited" about attending college and pursuing an art career, according to his sister.
"His love for art was amazing. That's all he did," his sister, Evelin Jimenez, told The Los Angeles Times.
Her parents told her that investigators confirmed her brother's identity through a DNA test, according to the Times.
Even though Ismael Jimenez was younger, his sister said she looked up to him like an older brother.
Based on reporting by The Associated Press.