An auxiliary power unit is being blamed for filling the cabin of an Air Canada Jazz jet on the ground in Regina with potentially deadly carbon monoxide.

A flight attendant and pilot headed out to the 50-seat regional jet to prepare it for a morning flight from Regina to Edmonton when they noticed something amiss: fumes, and the carbon-monoxide detector going off.

Regina Airport Authority CEO Jim Hunter explains fumes from a power unit keeping the plane warm apparently got into the cabin, but the two crew members smelled it right away.

Hunter says their blood oxygen levels were checked to ensure they were okay to fly, and they were.

No passengers were aboard the plane at the time.

The flight was delayed for close to an hour and a half while everything was checked out.