Dirt bikes and ATVs are illegal to operate on city streets, according to city officials. Operators can be ticketed, and vehicles confiscated.
A drone video shows hundreds of dirt bikes taking over the area of 6th Street and Lehigh Avenue at around 4 p.m.
Police began monitoring the large group around 4:30 p.m., officials say.
Officials also said the Philadelphia Police Department has designated police details that proactively monitor known gathering locations for biker groups.
The massive group of bikers made their way to Belmont Plateau, then onto Montgomery Avenue to City Avenue.
They eventually left the city and headed to Montgomery County.
Officials say smaller groups seemed to break away from the original one in Montgomery County.
Police say roughly 500 dirt bikers were involved in the incident and many committed traffic violations such as running red lights.
It is unclear why so many dirt bikers were on the roads.