Police officer Jason Lee says marchers were mostly peaceful in the protest against Proposition 8 that began Wednesday in West Hollywood and continued into Thursday morning.
But four people were taken into custody at the intersection of Hollywood and Highland when they tried to cross a line of officers.
Television cameras showed one of the protesters jumping on top of a police car. He was quickly wrestled to the ground by police.
Sheriff's Sgt. Kristin Aloma says two people were arrested in West Hollywood for disturbing the peace, and another was arrested for public drunkenness.
She says one deputy had minor injuries when he was hit by a car as he prepared to close an intersection before protesters arrived.