The NBA and Denver police are investigating an incident where a man, reportedly one of Denver Nuggets star Nikola Jokic’s brothers, was seen punching a fan after the team’s close 101-99 win over the Los Angeles Lakers in the NBA playoffs.

Videos from TMZ and other sources show the man climbing over seats to confront someone at Ball Arena, then punching them in the face.

TMZ reported that this happened on Monday night right after the Nuggets made an impressive comeback from being down by 20 points to take a 2-0 lead in the first-round series.

A spokesperson for the NBA stated on Tuesday that the league is looking into what happened.

The Denver police media relations unit mentioned in an email to The Associated Press that they are investigating, but no one reported the incident at the arena or after the game.

“No one has come forward as a victim of this incident,” the email stated. “The Department is working to identify the person in the video who was struck and encourages anyone involved or who saw this to contact the Denver Police Department.”