It happened around 11 a.m. near the intersection of Temple Street and North Alameda Street.
Los Angeles police say a man dressed all in black was riding a scooter when he fired a BB gun at nude cyclists.
Two victims were treated for lacerations at the scene. Further details about their conditions were not immediately available.
The suspect was taken into custody and will be charged with assault with a deadly weapon, and more charges are pending, according to LAPD.
Video from the scene showed a large turnout for the naked bike riding event. Video also appears to show a man being taken into custody by officers.