Investigators say human error is likely the cause of a fatal crash near Strathmore.

At around 3:45 p.m. on Wendesday a semi truck heading southbound, and with the right of way, t-boneda minivan that had seven people inside.

A 17-year-old boy driving the minivan and a couple, both 75-years-old, died at the scene.

STARS air ambulance took an adult female to Foothills Hospital. "Ground ambulances transported two female children to the Alberta Children's Hospital in life-threatening condition. Also, one adult male was transported to Foothills," says Adam Loria from EMS.

CTV News has learned the 12-year-old and 13-year-old girls, visiting from Nova Scotia, have been upgraded to stable condition.

A 23-year-old male remains in hospital in stable condition and a 22-year-old female is in hospital in critical condition.

The crash happened at the intersection of Township Road 234 and Highway 24 (Range Road 262).

The fire chief of Strathmore says the crash is the worst his crews have seen. He also says the intersection where it happened is known to be dangerous. "A lot of people, when they come east and west on Glenmore Trail, they just don't stop for the stop signs, they continue right on with no regard for the people going north and south," says Mark Hellman

Police say the investigation is ongoing but it appears unlikely charges will be laid.