Smoke filled the air in part of downtown Chicago on Saturday evening around the time that a loud boom was heard.
Around 7 p.m., smoke filled the air and caused low visibility between East Lake Street and Wacker Drive and North Michigan Avenue and Columbus Drive.
Video posted to social media showed a large plume of smoke rising into the air near the Fairmont Chicago hotel, located at 200 N Columbus Dr.
Another video shared on social media also showed drivers stuck in a traffic jam on Lower Wacker Drive as fire fighters and other officials responded to the scene.
An NBC Chicago producer in the area said he heard a loud boom just before smoke began filling the air, though it was not immediately known if or how the boom was related to the smoke.
No additional information was immediately available.
Check back for more on this developing story.