A WestJet flight had to make an emergency landing at the Calgary airport Thursday morning, CBC reported.
The Transportation Safety Board said the Boeing 737 Flight 113 took off for Vancouver at 6:30 a.m.
But at 10,000 feet, the fire warning went off in the cargo compartment, according to the TSB.
They deployed a fire extinguisher.
The flight returned to the Calgary International Airport about 15 minutes after departure.
"All guests and crew are safe and were unloaded after landing," WestJet public and media relations advisor Morgan Bell said in a statement to CBC News shortly before 10 a.m.
Bell said the passengers were all expected to get onto a new flight within the hour.
"We sincerely apologize for the delay and inconvenience to our guests but safety is always our first priority."
Bell said the plane had been removed from service for further inspection.
Two TSB investigators are on their way to Calgary.