A concert held in St. Louis to promote non-violence took a violent turn when one of the performers, R&B star August Alsina, got into a fight backstage with the event’s promoter, Loose Cannon Slim.

According to TMZ, Alsina, who performed at the concert alongside fellow artists Fabolous, Yo Gotti, and 2 Chainz, allegedly showed up late to the show, drawing the ire of Slim.

After exchanging words, things got heated quickly, with both sides throwing punches. In a video captured by TMZ, Slim goes to the ground, as Alsina’s friends try to pull the singer off of him. Fabolous can be seen holding a drink and watching the fight unfold toward the end of the video. Watch the full video at TMZ here.

According to St. Louis’ KPLR11, the State of Emergency 2 concert, held at St. Louis’ Chaifetz Arena, was billed as a benefit show for the “Put Down the Pistol” program, a program sponsored by local police departments and community organizations aimed at curbing gun violence.

Alsina reportedly had a great 2014, performing on collaborations with Nicki Minaj, Chris Brown, and Jeezy, among others. Songs from Alsina’s 2014 debut album Testimony wound up on the Hot 100 and Top 40 rap lists.