A woman who was six-months pregnant was among the seven people killed in a head-on collision in northern Alberta on Friday, a family friend says.

Courtney Penney and her husband Mark, 28, were passengers in a pickup truck belonging to their friends, Shannon and Trena Wheaton and their two sons, Timothy, 3 and Ben, 2, when it collided with another truck on Highway 63 north of Edmonton, April Anstey told CBC News.

Everyone in the Wheatons' truck was killed except Mark Penney and young Timothy, who were pulled from the wreckage and are expected to survive.

Anstey and her husband attend the Family Christian Centre, a church in Fort McMurray where Shannon Wheaton was a pastor. The Penneys were also members of the congregation, Anstey said.

"Mark is a fantastic guy, always up to help anyone," Anstey said. "Always up for a great laugh, great guy to be around."  

The couple were eagerly awaiting the birth of their first child, she said: "They were so excited — beside themselves. Everything they talked about was 'baby, baby, baby.'"

'They were so excited — beside themselves. Everything they talked about was 'baby, baby, baby.'— April Anstey on her friends Mark and Courtney Penney 

The Wheatons and Penneys "were inseparable," Anstey said. "Mark's best friends were Shannon and Trena. I don't know what it's going to be like when he realizes he's lost his wife, his baby and his best friends."

Shannon Wheaton's loss is having a "big impact on the community," Anstey said.

"He just touched so many hearts," she said, "left a beautiful ministry."

Courtney Penney was originally from Dartmouth, N.S., while Shannon Wheaton had grown up in Fredericton, a small community in Newfoundland's Gander Bay. He had relocated to Fort McMurray with his family in 2010.

Anstey, who has lived in the Fort McMurray area for 16 years, said she has never had a close call on Highway 63 — a notorious stretch of road that has seen scores of accidents in recent years — but has heard of many others who have.

Her advice? 

"Just slow down. This could have been avoided if people just slowed down, and then we would not be mourning seven lives. 

"I count it as a privilege to have known them," Anstey said. "I really do."

A memorial service for the victims was held Sunday at the Family Christian Centre in Fort McMurray.