Three people are dead following a crash at a rural intersection near Breton, Alta., Monday night.

A car travelling south on Range Road 40 was hit by a pickup truck headed east on Highway 39 shortly before 7:30 p.m.

Three of the four people in the car died at the scene, while the fourth was airlifted to hospital, said RCMP Staff Sgt. Brian Jones.

Police have identified those killed in the crash as William Saunders, 20, Spencer Gustafson, 21, and Morgan Hetchler, 15.

An 18-year-old woman was airlifted to hospital where she is in stable condition.

Investigators believe the car was travelling "well in excess of the speed limit," according to a statement released Tuesday afternoon, and that the driver failed to obey a stop sign at the intersection.

The truck, which was travelling at highway speed, hit the car broadside at the intersecion.

The driver of the truck, a 31-year-old man, was treated in hospital for minor injuries and released.

RCMP Cpl. Rod Klenk said police hope to determine why the car failed to stop.

"We don't know if it was alcohol [or] distracted driving," Klenk said. "We're trying to investigate that."

Road and weather conditions did not appear to be factors in the crash, Jones said.

Police say none of the people in the car were wearing a seatbelt. Three of them were thrown from the car, including the 18-year-old woman who is in hospital in Edmonton.

Grief counselors spent the day helping staff and students at Breton High School. Two of the victims had recently attended the school and another was a current student.

Klenk said word of the crash began circulating on social media websites and reached the victims' families before police were able to reach them.

"Unfortunately Facebook got to the families before we did," he said. "It was not a good scene in a couple of the homes."