The NBA is investigating an alleged assault by Nikola Jokic’s brother in the stands of Monday night’s buzzer-beater game, TMZ Sports reports. A video circulating on social media shows the Denver Nuggets star’s brother Strahinja in the Denver crowd during the Nuggets’ win against the Los Angeles Lakers. Strahinja can be seen climbing down over the seat in front of him toward another attendee before apparently punching the man in the face. Jokic’s other brother, Nemanja, can be seen shouting at the man alongside his brother. TMZ Sports was able to confirm the incident with witnesses at the game, which the Nuggets won 101-99. The cause of the altercation is unknown. The behavior in the video appears to be in violation of the NBA’s fan conduct advisory, but it’s unclear whether Jokic or his family members will face disciplinary action.