(AP) — Police say gunfire erupted at a Denver park today, wounding two people and sending tens of thousands gathered for an annual pot celebration fleeing the area.

A crowd of marijuana smokers expected to swell to 80,000 had gathered at the park to mark the counterculture holiday known as 4/20 on the first celebration since Colorado and Washington made pot legal for recreational use. The shooting happened at about 5 p.m. and shortly after pot smokers shared hugs and joints in a mass 4:20 p.m. smoke-out.

A police spokesman says both of the shooting victims were taken to a hospital with injuries that did not appear to be life-threating.

Witnesses say they heard three or more shots which quickly dispelled the festive atmosphere, with police swarming the scene.

Aerial footage shows the massive crowd frantically running from the park.

A sizable police force on motorcycles and horses had been watching the celebration. But officers didn’t arrest people for smoking in public, which is still illegal.