Crews are searching for a four-seater Piper Warrior aircraft that was due to land in Kamloops Thursday but never arrived.

There were two people on board the small, light plane. The Cranbrook RCMP have identified them as pilot Alex Simons, 21, and Sidney Robillard, 21. Both are from Kamloops.

The Joint Rescue Coordination Centre in Victoria is leading the search with a helicopter, an airplane as well as military aircraft that joined Saturday. Spokesman Lt. Greg Menzies says the search in the mountainous, heavily treed area with shifting weather has been challenging.

"There're parts of the mountain range that extend 10,000 to 11,000 feet," he told CTV News. "Because of the inclement that the crews are facing today, with a cloud ceiling of only 7,000-8,000 feet, there's still a lot of area that hasn't been searched yet. "

Jason Kobi, acting regional manager of the Transportation Safety Board, said the plane was last seen when it stopped for fuel in Cranbrook, B.C. Thursday. It departed Cranbrook around 3 p.m. and was supposed to land in Kamloops at 4 p.m., but never showed up.

The search and rescue mission began Thursday and continued all of Friday, but so far it hasn't turned up any sign of the missing plane or its passengers.

Simons and Robillard took off from Excel Flight Training school in Lethbridge, Alta.; their ultimate destination was Kamloops.

There has been no contact with either of them, and Cranbrook RCMP are asking anyone with information to contact local police.