Police in Alberta are investigating a fiery head-on collision involving two pickup trucks that killed seven people on a busy stretch of highway between Edmonton and Fort McMurray.

The crash occurred on Friday in snowy conditions on Highway 63 near Wandering River, which is about 250 kilometres north of Edmonton.

"We do know that through preliminary reports that there was a northbound pickup truck carrying three occupants. It pulled out to pass another vehicle and collided with a southbound pickup truck carrying six occupants," said RCMP Const. Christina Wilkins.

RCMP confirmed that six of the nine people involved in the collision died at the scene of the crash. The seventh person, a teenage girl, later died in hospital.

Two survivors — a young boy and a 34-year-old man — were badly injured.

The accident happened about 250 kilometres north of Edmonton on the highway that connects the oilsands in Fort McMurray with the rest of the province. (CBC)

Police said a significant fire erupted following the collision, and described the wreckage-strewn scene as "horrific."

Two of the deceased had been travelling in the northbound pickup truck with the teenage girl, who was pulled from the burning truck by passing motorists before emergency crews arrived, police said.

The teenager, the boy and the 34-year-old man were airlifted to Edmonton hospitals, where the teen succumbed to her injuries.

Traffic in both directions is being rerouted to secondary Highway 881. Police had advised drivers to stay off highways south of Fort McMurray due to a spring snowfall and reduced visibility.

Highway 63 reopened to traffic late Friday evening, after being closed for about eight hours due to the crash.

One of Alberta's deadliest highways

The highway is a busy route stretching north of Edmonton to Fort McMurray and north to the oilsands, where thousands of people work and tonnes of material and equipment move daily.

Two years ago, volunteer firefighters from Wandering River stopped responding to accidents on the highway because they found the work overwhelming.

In 2011, the provincial government and Athabasca County invested $1.3 million to hire more emergency responders to cover the route.

Between 2001 and 2005, more than 1,000 crashes killed 25 people and injured 257 others on the highway.

In 2006, after years of public pressure, the Alberta government announced that it would twin a 240-kilometre stretch of the road. As of October 2009, 16 kilometres had been twinned.

With files from The Canadian Press