A clergyman, his wife and one of their children are among the victims of a horrific highway crash in northern Alberta that claimed seven lives on Friday.

Rev. Shannon Wheaton, his wife Trena and son, Ben, 2, were killed in the head-on collision on Highway 63 between Edmonton and Fort McMurray. Their elder son Timothy, 3, is in hospital and expected to survive. The tot and a man, 28, who the RCMP initially said was 34, were the only survivors.

A man, 34, two women, aged 34 and 28, and a girl, 11, also died when the two pickup trucks collided. Their names have not been made public.

Wheaton, a Fort McMurray pastor from Newfoundland and Labrador, moved to Alberta with his family in 2010 to work with the Family Christian Centre.

"He was one of the most gentle and generous individuals I have ever known."— Rev. Edwin Rideout, Family Christian Centre.

Rev. Edwin Rideout, lead pastor at Family Christian Centre who worked with Wheaton in both Newfoundland and Alberta, called him "one of the most gentle and generous individuals" he has ever known.

"His passion for God, the church and the community was exceptional," Rideout told CBC News in an email. "We are providing grief counselling and soul care for the families involved."

Fort McMurray resident David Pollard said Wheaton's death is a great loss to the church community.

"He did a tremendous amount of work in relation to our children's ministries," said Pollard, who added Wheaton had a way of bringing people together through leadership.

Wheaton's online staff profile, which lists him as the family ministries pastor, says he was "married to the lady of his dreams" and was the father of two boys. It also notes his passion for connecting children with their faith.

Although the website has no official comment on the tragedy, a special announcement notes that there will only be one service this Sunday and that "prayers are very much appreciated."

One of Alberta's deadliest highways

RCMP say they're still investigating the cause of the crash.

Six of the nine people involved in the collision died at the scene of the crash, RCMP said. The seventh victim, the 11-year-old girl, later died in hospital. The RCMP said that several people helped victims at the scene of the crash and tried to extinguish the flames "with little regard for their own personal safety."

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

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

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. The Alberta Transportation Ministry told CBC News that 33 kilometres of Highway 63 have already been twinned. Another 36 kilometres will be completed by fall 2013.

Pollard and other members of the community say the government should pick up the pace to improve safety.

"At the rate that they're going there now and the rate that the actual community of Fort McMurray is growing — they're really falling behind and dropping the ball," Pollard said. "There's a lot of people that have died there. And you could quite possibly call it the highway of death because there's so many people that have died — needlessly."