The incident occurred at 3 a.m. Friday.
People.com said a sheriff's deputy in a marked black and white radio car was stopped at an intersection, preparing to turn right when Bynes tried to pass him in her black BMW and collided with the right rear quarter panel of the radio car.
Only minor damage to both cars was reported.
The actress was arrested and bail was set at $5,000, People.com said. It was unclear if she has been formally charged with DUI or released from police custody.
Bynes, 26, is the former star of the children's sketch comedy series "The Amanda Show." Her film credits include "Hairpsray" and "What a Girl Wants."