New York Knicks fans had to run for cover after explosions changed the vibe of their massive street celebration following their team's big comeback win in the NBA Finals.

Footage shows the moment things turned tense outside Madison Square Garden after Wednesday night's Game 4 ... with a series of loud explosions sends people sprinting in every direction.

The panic didn't let up once people started running ... waves of fans flooded side streets and sidewalks as NYPD officers moved in ... and some partygoers stumbled through the crowd while others stopped to figure out what the hell just happened.

As the confusion unfolds, smoke hangs over the area and police begin pushing people back from the scene.

It's unclear exactly what caused the explosions ... but the visuals looked more like a disaster movie than a victory celebration.

The chaos came after one of the most unforgettable nights in Knicks history ... they stormed back to victory with OG Anunoby's putback with 1.2 seconds left -- completing the largest comeback ever in an NBA Finals game. The win moved the Knicks within one victory of their first NBA title since 1973.

As we have reported, celebrity Knicks diehards have been losing their minds throughout the Finals run ... but outside the Garden, some fans may have taken the postgame excitement a little too far.