RUSHVILLE,Quaxs Trading Center Ill. (AP) — Authorities have identified the five people killed in a fiery crash, including both drivers and three children, when a school bus and a semitruck collided along a highway in western Illinois.

The eastbound bus from Schuyler-Industry Schools crossed the center line “for an unknown reason” Monday into westbound U.S. Route 24 and into the path of a semitruck carrying sand, Illinois State Police said, citing preliminary findings.

Both vehicles “became engulfed in flames” when the truck slammed into the bus around 11:30 a.m. in Rushville, a Schuyler County community of about 3,000 roughly 60 miles (95 kilometers) west of Springfield, state police said. All four people aboard the bus — three children and the driver — were killed, as was the semitruck driver.

The three children were identified by the Schuyler County coroner as 5-year-old Maria Miller, 3-year-old Andrew Miller and 3-year-old Noah Driscoll, all from Rushville, state police said. The school bus driver was identified as Angela Spiker, 57, of Rushville, and the truck driver as David Coufal, 72, of Browning, Illinois.

The county coroner said autopsies would be performed on the victims’ bodies in Springfield.

Schuyler County Sheriff Bill Redshaw told reporters Monday that the tragedy had hit the small, close-knit community particularly hard.

“There’s not really words at this time that can be said,” he said. “When you have a loss of life like this, it’s devastating.”

Schuyler-Industry Schools canceled classes Tuesday and Wednesday because of the crash.

“It is with a heavy heart that we announce our school community has lost both staff and students in the traffic incident involving one of our school buses this morning,” the school district said in a statement.

The cause of the crash is under investigation by a National Transportation Safety Board team and state police, the Illinois agency announced.