All three children on a school bus were killed when it veered into oncoming traffic and collided with a tractor-trailer in western Illinois on Monday morning, authorities said.

The drivers of the bus and truck also died, Illinois State Police said.

The vehicles were engulfed in flames, and there were no survivors, Capt. Jody Huffman said at an afternoon news conference.

“No one should have to go through this horrible situation,” Huffman said.

It’s not clear why the bus veered into oncoming traffic about 11:30 a.m. on Route 24 in the small city of Rushville, she said. State police took over the investigation.

The names of those killed have not been publicly released.

Sheriff Bill Redshaw said the loss was quickly felt in the area of the crash, Schuyler County, which has a population of less than 7,000 and occupies 441 square miles on the west side of the state.

“It’s a close-knit family,” he said, describing his community. “To have loss of life like this, it’s devastating.”

The bus was headed east, and the truck, transporting sand, was going west when the collision happened, according to Huffman and a state police statement.

U.S. Route 24, a major thoroughfare for the county that ultimately connects it to Kansas City, Missouri, was the subject of an “extended closure” as authorities continued to investigate what caused the bus to move into oncoming traffic, the agency said.

The weather was fair, with clear skies at the time of the crash, according to National Weather Service data.