Marie Ann McCann, 77, and Lyle Thomas McCann, 78, left Alberta for B.C. on July 3 and have not been seen by their family since. (RCMP)The family of an Alberta couple missing for more than a week is devastated by their disappearance.

Lyle Thomas McCann, 78, and his wife, Marie Ann McCann, 77, left St. Albert on July 3 headed for B.C. They were driving a 1999 green and white Gulf Stream Sun Voyager recreational vehicle and towing a light green Hyundai Tucson.

"Our whole family is just devastated by this," their son, Bret McCann, said at a news conference in Edmonton on Tuesday. "It's just devastating to us all. It's just unbelievable, really. We're a really close-knit family."

RCMP confirmed Monday that the McCanns' motorhome was found on fire at the Minnow Lake campground near Edson, Alta., on July 5. Their SUV, bearing Alberta licence plate ZPK 289, has not been found.

Bret McCann, shown at Tuesday's news conference in Edmonton, said his parents were experienced travellers. (CBC)The McCanns were headed to Abbotsford, B.C., to meet their daughter, Trudy Holder, at the airport on July 10 but never showed up.

"We got into the airport waiting area and they weren't there and that is like totally opposite my parents," Holder said Tuesday in Vancouver.

She called the RCMP after learning her parents failed to show up at the home of friends they were supposed to visit along the way.

Bret McCann said his parents were experienced travellers who would spend several months in the U.S. during the winter.

McCann's father, a long-haul truck driver for much of his working life, spent a lot of time driving through Alberta and B.C.

"They were in their late 70s, but they were quite vigorous," McCann said, adding that the family was comfortable with the couple's ability to travel.

Ground search underway

Since July 10, the RCMP have performed an air search of 259 square kilometres, interviewed witnesses, searched the couple's cellphone records and used a police dog in the search, RCMP Sgt. Patrick Webb said at a news conference Tuesday.

Police are looking for this light green Hyundai Tucson SUV with Alberta licence plate ZPK 289. (RCMP)Police also checked the McCanns' bank accounts, which showed nothing unusual, Webb said.

Webb added there was a ground search carried out Tuesday in the area where the burned motorhome was found. Civilian search and rescue teams from Brazeau, Parkland and Hinton were taking part.

The RCMP's forensic identification section is also involved in the investigation.

"At this point, the focus is on finding the McCanns," Webb said. "We need the public's help in doing this."

Bret McCann, who has started a Facebook group to try to help find his parents, is trying to keep positive.

"We're very hopeful that the public can help us, through this SUV, find our parents," he said.

In B.C., McCann's sister, Trudy Holder, is also trying to stay positive and hopes the RCMP will get a crucial break in the case.

"Keep the tips coming in, please. Keep up our hope," she said.