CHICAGO, IL — Smoke filled the C concourse in Terminal 1 at O'Hare International Airport Thursday evening. Several air travelers tweeted images of the smoke-filled terminal as people wandered through with their carry-on baggage.

The smoke reportedly was coming from the "Nuts on Clark" shop inside the terminal, a fixture at Chicago's airports where nuts and fresh popcorn is sold. Officials said a popcorn machine overheated and caught fire.