A Britney Spears concert in Connecticut turned into a three-ring "Circus" when an overzealous fan hopped onstage to boogie with the pop princess -- and Britney screamed!

When Kyle King, 20, jumped onstage (about 2:20 into the video above) Brit stopped singing "Womanizer," screamed and visibly shook with fear. Her backup dancers yanked him away. King was arrested after the incident and released Sunday morning on $250 bail.

King is due in court on June 18 to face the charge of "breach of peace."