A bartender at Comet, who said he didn't see a gun himself, told News4 everyone inside started to panic as the man walked to the back of the restaurant. Customers and employees evacuated.
One shot was fired into the floor, but no one was hurt, police said.
and here: https://www.buzzfeed.com/johnstanton/pizza-gate-arrest
DC Police responded to a call at 2:59 p.m. ET from a witness who said they saw a man armed with an assault rifle had entered Comet Ping Pong, a bar and music venue in the upscale Friendship Heights neighborhood of Northwest Washington, department sources said.
DC Police Chief Peter Newsham told reporters that the suspect fired more than one shot into the ground while inside the bar.
Shortly before 4 pm, police took the man into custody after he left the bar.
Although police brought in the bomb squad, sources said it was a precautionary measure and the suspect did not specifically say he had a bomb.
I suspect that this guy was trying to find out for himself what was happening at this place.