Police are investigating a bloody brawl that broke out between sports fans at a bar in Massachusetts over the weekend — which got mistaken for a postgame Yankees-Red Sox scrum.

Footage of the melee shows a man in a Boston jersey and baseball cap swinging a chair and assaulting several people inside the establishment.

In another shot, a black-clad man can be seen throwing what appears to be shattered glass in the face of another individual, who falls to the ground holding his head as his eye starts to bleed. The man in the Red Sox gear appeared to be retaliating.

Bystanders look on in horror, screaming and scrambling away from the violence as the brawl unfolded. Footage of the mayhem was being shared online Monday night following the Yankees’ 16-to-1 loss to Boston — causing many to think it happened after the game.

“F–k you!” the jersey-wearing man can be heard screaming before being carried out of the bar by a woman, according to the video.

The bloodied victim can be seen waling past the camera a second time, shaking his head, as others in the background try to pick another person off the floor.

Instagram user @whodaf–kwannago2prison was one of several people who posted the fight video on social media and thought it stemmed from the game.

Police in Massachusetts, however, later confirmed that the incident happened at the Brickhouse Tavern and Tap in Methuen.

“With the video we can freeze it, we can enhance it, and we can see if we can identify, most importantly, the perpetrator who threw the glass,” Methuen police Capt. Jim Jajuga told WHDH.

“That’s our number one goal, and then we’ll see if we can identify the other parties.”