Halifax fire platoon Chief Scott Shaffner said six fire vehicles responded to the airport. He also said there were two platoon chiefs as well as paramedics at the scene.
Airport spokesperson Ashley Gallant told CBC News that Delta Airlines flight DL66, which left Atlanta, Ga., headed for Zurich, Switzerland, was suffering from an "oxygen maintenance issue."
Gallant said there were 139 passengers and crew on board the plane.
She said Delta Airlines has dispatched another plane to take passengers to their final destination, Zurich.
According to the flight-tracking website, flightradar24.com, the plane is a Boeing 767. The flight turned back toward mainland North America, after reaching south of Newfoundland.
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