The crash on a two-lane portion of Highway 63 near Boyle, about 100 miles north of Edmonton, occurred Friday afternoon, the Edmonton Journal reported.
Police said the children who died were a 2-year-old boy, an 11-year-old girl and a teenage girl.
Family members and friends identified Shannon Wheaton, family ministries pastor at the Fort McMurray-based Family Christian Center, as one of those killed in the crash.
"Pastor Shannon was very family-oriented and did his ministry with children from the depths of his heart," Pastor Robert Parsons said Saturday. "He loved the kids and the kids loved him."
Police said a northbound pickup carrying three people pulled into the oncoming lane to pass and collided head-on with a southbound pickup carrying six passengers.
All three occupants of the northbound truck died, as did four from the other truck, including a teenage girl pulled from the truck by passing motorists and who died at Stollery Children's Hospital in Edmonton.
A 34-year-old man and a 3-year-old boy who survived the crash suffered serious injuries. The boy was in stable condition at Stollery Children's Hospital
The 34-year-old man was in serious but stable condition at the Royal Alexandra Hospital in Edmonton.
The Journal said the nearly 150-mile stretch of Highway 63 linking the the oil sands with the rest of the province is known as one of the Alberta's deadliest roads.