Heavy machinery was cleaning up debris at the Thunder Bay airport Thursday after a severe thunderstorm blew off part of the metal roof of the air terminal building and damaged 12 cars.

A portion of the roof blew off Wednesday night, hurling debris into a parking lot, where it crushed and damaged some cars, police said. There were no reports of injuries.

The parking lot was littered with bent steel and broken glass Thursday but the local airport authority said the airport "remains fully operational."

Airport CEO Scott McFadden helped with the cleanup effort.

"We've been engaged in a cleanup since immediately after the storm so we've got the terminal frontage functional again and we're working on cleaning up the parking lot," he said.

Parking will be limited until the damaged cars are removed.

During the storm, winds uprooted many trees. At one point about 6,000 people in the area were without power, though it was later restored.