Celtics fans brawl at NBA Finals watch party in ugly scene at TD Garden

What appears to be a younger fan can be seen repeatedly punching and pummeling an older fan, who is down on the ground on the stairs when the recording begins.

The younger fan lands multiple punches before other fans and security break it up.

The younger fan then shouts “you f–king p—y” as he’s restrained.

The older fan, who was also being restrained by arena security, then got in a brief fight with a different fan before quickly being pulled apart.

The Celtics had cruised through the playoffs and NBA Finals, and Friday’s loss marked their first since May 9 in the second round.

They had been riding a 10-game playoff winning streak, but now return home to Boston holding a 3-1 series lead.

“I thought the guys came out with the right intentions. I just didn’t think it went our way, and I thought Dallas outplayed us. They just played harder,” head coach Joe Mazzulla said after Game 4. “You have to prepare to put yourself in the best possible position, but it doesn’t guarantee anything.

“At the end of the day, we have to just maintain our process and get ready for Game 5.”