Police are still searching for the suspected gunman who opened fire during a celebration of the first 4/20 day since Colorado legalized marijuana.
Initial reports indicated that close to a dozen shots were heard around 5 p.m. on Saturday, with Denver police reviewing surveillance video of attendants at the park.
Police spokesman Sonny Jackson explained during a press conference that a suspect is shown in the video walking in a crowd that was moving away from the scene of the shooting after the gunshots rang out.
The suspect, a black male who was wearing a brown and white checkered shirt, can be seen about six seconds into the video, Jackson added. The police gang unit has taken over the investigation, although it isn't yet clear if gangs were involved.
"We are seeking this individual as we believe he assisted the primary suspect after the shooting," Jackson added.
Witnesses who were at the marijuana-themed event said that the atmosphere was lighthearted, but instantly turned into chaos as thousands of people scattered in the downtown Civic Center Park.
One of the victims was shot in the leg and was attended to by a fellow smoker.
"I saw him fall, grabbing his leg," Travis Craig, 28, who was at the celebration, told Fox News. He witnessed the shooting and said he used a belt to apply pressure to the wound.
"He was just screaming that he was in pain, and wanted to know where his girlfriend was. She was OK. And then the cops showed up real quick, like, less than a minute. They put him on ambulance and left," Craig added.
Origins of 4/20 being the day to smoke marijuana are unclear, but the annual event held in Colorado is estimated to have drawn nearly 80,000 people after recent laws in Colorado and Washington made marijuana legal for recreational use.