Thick, dark smoke filled the sky in Midtown at the start of the St. Patrick's Day parade.

The FDNY says there was a fire in the HVAC system. No one was hurt.

The fire began on the roof of a building located on East 43rd Street, just around the corner from the starting point of the parade.

Paradegoers saw firetrucks and other emergency vehicles rushing to the scene.

Emergency operations are still ongoing, according to the FDNY.