The scuffle at West Towne Mall began after the girl in the bunny suit -- a 15-year-old high school freshman -- removed the head part of her costume and set it down, Madison Police Department spokesman Russell Henderson said Tuesday.
"Her assistant pushed her and she fell over her head," Henderson said. "The Easter Bunny then got up and punched her assistant a couple of times."
The girl's 20-year-old assistant also was arrested after the fracas Monday. The girl was released to her parents. The assistant was booked and released.
Henderson said it wasn't clear what the two were arguing about.
Jodi Coyer, marketing director for the mall, said the company that sent the battling bunny has fired the teen-ager and sent over a replacement.
"Obviously we don't tolerate this kind of behavior and wanted to make sure everyone understands we don't," Coyer said.
She added that the scuffle happened while the two employees were on a break and was not witnessed by any mall shoppers.