Authorities asked a judge for the warrant after undercover officers attending separate events in May and July witnessed people openly selling and using drugs and "head shops" selling drug paraphernalia, Brooks said.
Under a settlement of a federal religious rights lawsuit against the county by church leader church leader William Pritts last March, the church was allowed to hold a limited number of concerts at Pritts' property in Acme, about 35 miles southeast of Pittsburgh. Neighbors had complained about traffic and noise, and officials said they were concerned about illegal drug use.
The 21 arrested at Saturday's concert - which was attended by 400 to 500 people - face charges ranging from misdemeanor drug possession to felony possession with intent to deliver. More arrests are possible, Brooks said.
Large amounts of drugs including marijuana, LSD, and hallucinogenic mushrooms were collected, Brooks said, but he didn't say specifically how much.
Brooks said he initially doubted the undercover officer's accounts of drug use at earlier events.
"They made it sound like Woodstock on steroids," he said. "But within minutes of getting out of the undercover vehicle they observed people walking around smoking marijuana in the open. And we never asked to purchase drugs; people came up to us offering drugs ... all we did was stand there like patrons listening to the music."
Pritts has an unlisted number, and the church's phone rang unanswered Sunday. The church's Web site includes a list of concert rules, including no illegal drug use or underage drinking.
The church calls music the "universal language" that can break through prejudice and help people attain their full potential. "Music, Nature, Humor all help us to achieve happiness, and to see the essence of life and existence," the Web site says.
