Three children who were killed in a highway collision northeast of Calgary Wednesday night were travelling from the state of Washington with their parents, who survived the crash, RCMP say.

An infant girl, a 16-year-old girl and an 11-year-old boy were declared dead at the scene after the SUV they were in collided with a semi-truck at about 5:45 p.m. at the intersection of Highway 36 and Highway 570 south of Hanna, a town 215 km northeast of Calgary. 

The children's mother, 32, was flown to Foothills Medical Centre in Calgary by STARS air ambulance and their father, 44, was taken to the hospital in Brooks. Both are listed in stable condition, said RCMP Corp. Laurel Scott.

Hanna crash kills 3 family members

The crash happened early Wednesday evening at Highway 36 and Highway 570, about 50 kilometres south of Hanna, Alta. (Silvana Benolich/CBC)

"This is certainly a very tragic situation for this family, and for these parents," she said.

A collision analyst went to the scene of the crash Wednesday night to begin investigating the cause of the crash.

"The process now is we wait to get his report," she said.

Hanna crash kills 3 family members

Tire tracks can be seen near the crash site south of Hanna, Alta. (Silvana Benolich/CBC)

It's believed the SUV was travelling west on Highway 570 when it collided with the southbound truck on Highway 36.

There is a stop sign on Highway 570.

The driver of the semi was taken to Hanna General Hospital and has since been released.

Hanna Mayor Chris Warwick says installing flashing lights before the stop sign on Highway 570 might help prevent similar tragedies.

Doug Anderson, who has a farm near the crash site, agrees improvements could be made to the intersection.

"A bigger stop sign would help here and maybe photo radar," he said.