Video of the incident shows the gun falling out of the agent's trousers as he does a backflip.
As the agent picks up his weapon, it discharges, hitting a man in the crowd in his lower leg.
The single shot rang out around 12:45 a.m. inside Mile High Spirits Tasting Room on Lawrence Street and 22nd Avenue.
Denver district attorney spokesman Ken Lane said by email on Sunday morning that the DA's office had no comment as the incident remains under investigation by the Denver Police. In August, an agent with Immigration and Customs Enforcement on vacation accidentally shot himself while going through a security line at Orlando International Airport. It appears not everyone in the crowd realized what happened, but many begin to react as the agent places the gun back in his waistband and covers it with his shirt before walking off.
The agent was doing a back flip when the firearm fell out of his waistband and went off when he picked it up, accidentally shooting a bar patron.
Julie said she asked the DJ to turn off the music.