Jazz Aviation says an Air Canada Express flight bound for Vancouver had to make an unscheduled landing shortly after leaving San Francisco International Airport Sunday morning due to a smoke alarm.

Company spokesperson Manon Stuart says crew members on flight AC8839 the rear lavatory smoke detector went off shortly after taking off at 8:18 a.m.

Half an hour later, the plane had landed back on the tarmac and Stuart says the crew performed an emergency evacuation as a precautionary measure.

He says 74 passengers and four crew members got off the plane safely and shuttle busses transported passengers back to the terminal, while emergency vehicles met and inspected the plane.

He says there was no smoke in the cockpit.

San Francisco airport duty manager Dennis Zamaria says the U.S. Federal Aviation Administration is investigating the source of the smoke, while Stuart says Jazz Aviation’s maintenance team is also inspecting the plane in order to proceed with the necessary repairs.

Stuart says another aircraft and crew were dispatched to resume the flight to Vancouver.