University of Colorado police have posted 150 photos of people who attended an annual gathering on campus last Friday that celebrates marijuana.
Police are offering 50-dollar rewards for information about the people, many of whom are shown with hand-rolled cigarettes, glass pipes or bongs. One young man was streaking.
Authorities say they were trespassing on Farrand Field, despite signs and security posted to keep them away.
About 25-hundred people attended the event, but police believe less than half were using the drug. A local restaurant gave away sandwiches, while people dressed in costumes and danced to the beat of drums.
The gathering occurs on campus at 4-20 p-m on April 20th each year.