Cheyenne, Wyoming - About 400 members of the Rainbow Family threw rocks and sticks at 10 federal officers as they tried to arrest a member of the group, the U.S. Forest Service said Friday.
Five members of the group were arrested and one officer was slightly injured. A government vehicle was also damaged.
About 7,000 members of the Rainbow Family are camping this year on Forest Service land near Big Sandy. The Rainbow Family is a loose affiliation of eccentrics, young people and hippie types who choose a forest each year in which hold a weeklong national gathering.
Ten Forest Service officers were patrolling the main meadow of the Rainbow Family's camping area Thursday night and apprehended one person described as being uncooperative, Rita Vollmer, spokeswoman for the U.S. Forest Service, said in a statement Friday.
"Officers began to leave the gathering site with the subject and were circled by more Rainbow participants that began to physically interfere," Vollmer said.
About 400 Rainbows surrounded the officers trying to leave, she said.
"The mob began to advance, throwing sticks and rocks at the officers," Vollmer said.
Mary Cernicek, spokeswoman for the Bridger-Teton National Forest, said Friday that more officers arrived to help. Officers fired "pepper balls" - similar to paint balls but containing a pepper solution - to control the crowd, she said.
State troopers have also arrested two people this week on felony drug charges for allegedly possessing 96 hits of LSD, said Sgt. Stephen Townsend of the Wyoming Highway Patrol.
The Rainbows and federal officers have clashed repeatedly in years past, and the Forest Service in 1998 established a national response team to deal with the group. Officials have complained that the gathering can ruin forests, with the group saying members clean up and reseed afterward.