Punches were thrown heading into a RIDE check in Belleville Saturday night.
Around 10:45 p.m., city police were set up near the CN overpass on North Front Street.
Around midnight, officers say a car rolled up and one passenger was throwing punches at another in the back seat.
A 21-year-old Belleville woman was arrested for breach of the peace.
Alcohol was said to be a factor in the incident.
A small amount of marijuana was seized.