DENVER (AP) - Denver police say one person has been shot in the leg and another is down with unknown injuries after shots were fired at a marijuana celebration held to mark the counterculture holiday 4/20. Witnesses say they heard three or more shots about 20 minutes after 4:20 p.m. Police swarmed the scene, and crime tape was around the pavilion where the celebration was being held. The pot celebration Saturday was the first since Colorado and Washington made marijuana legal for recreational use. A sizable police force on motorcycles and horses watched the celebration. But officers didn't arrest people for smoking in public, which is still illegal. A crowd estimate wasn't immediately available, but organizers predicted some 80,000 at the nation's largest 4/20 observation.