ORLAND, Calif. — Three months after sharing a picture-perfect Christmas engagement outside the Louvre Museum in Paris, Michael Myvett and Mattison Haywood were on another adventure, accompanying 44 teenagers on a visit to Myvett’s college alma mater.

The Los Angeles couple volunteered to be chaperones on a charter bus carrying high school seniors on a 650-mile trip from Southern California to Humboldt State University. They died together when a FedEx tractor-trailer slammed into the bus, in a fiery crash that also killed five teens, another adult chaperone and the drivers of both vehicles, officials and relatives said.

That Myvett, who graduated from Humboldt State with a psychology degree in 2007 and worked with autistic children, was eager to make the trip with the fiancé to whom he had proposed on bended knee made sense to friends and co-workers.

Haywood was “the love of his life” 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 peoples’ achievement of their dreams,” said Kyle Farris, a colleague at the Center for Autism and Related Disorders in Torrance.

The bus carried a lot of dreams. It was one of three the northern California college chartered to bring prospective students, many of them hoping to be the first in their families to attend college, to tour its campus before they got busy with prom and graduation.

“I can only imagine the excitement of these high school students as they were on their way to visit a college campus, and the pride of the adults who were accompanying them,” U.S. Secretary of Education Arne Duncan said in a statement. “Our young people are our greatest treasure, and this loss is heartbreaking.”

Desperate families awaited word about loved ones Friday, while investigators tried to figure out why the southbound FedEx truck swerved across a grassy divide about 100 miles north of Sacramento before sideswiping a car and slamming into the tour bus, which burst into a furious blaze.

The Serrato family, whose identical twin 17-year-old daughters set off on the adventure on separate buses Thursday, had a panicked, sleepless night. Marisol made it to their destination, Humboldt State University, but the family had no word on Marisa, who had been aboard the now-gutted bus, for nearly 24 hours.

They received the official word Friday evening when dental records confirmed Marisa was among the dead.

“Marisol is devastated,” the girls’ 23-year-old brother Miguel Serrato said.

Another student feared dead was Adrian Castro, 19, a senior and a football player at El Monte High School east of Los Angeles. Castro was considering going to a state university closer to home but decided to give faraway Humboldt, home of sports teams known as the Lumberjacks, a chance, his father, Raul Castro, told the San Gabriel Valley Tribune.

“He told me two days ago, ‘Should I go up and check it out anyway?”’ said Raul Castro, who dropped his son off to meet the bus on Thursday morning. Later that night he got a call from Adrian’s mother, who said she had heard from the California Highway Patrol that the young man had died.