Philadelphia Police seized dozens of ATVs and dirt bikes and arrested four people Saturday after riders took to the streets in preparation for a concert from local hip hop star Meek Mill.

Police told NBC10 they received word on social media that a "ride out" in honor of the 27-year-old rapper, born Robert Williams, was set to take place. Meek grew up in Philadelphia and was active in the dirt bike riding community. His “Welcome Back” concert began at 8 p.m. Saturday at the Wells Fargo Center.

"We just got wind on social media that there might be a ride out for this concert," said Philadelphia Police Chief Inspector Dennis Wilson.

A citywide crackdown began at noon. The riders were spotted in North Philadelphia and Hunting Park throughout the day. Police told NBC10 they followed one group of riders who traveled from North Philadelphia to the Philadelphia Zoo before abandoning their vehicles and then running into a nearby garage. Police then took the vehicles without incident.

In all, police confiscated 68 dirt bikes and ATVs as well as three trucks.

"Two of the trucks were transporting stolen ATVs and dirt bikes," Wilson said. "Most of these seizures were a result of bikes that were trucked in. Some of these dirt bikes were just abandoned. The riders, when we closed in on them, jumped off and ran away."

In addition to the seized vehicles, police also made four arrests.

"One of the individuals we stopped had a gun on him," Wilson said. "He was arrested for the gun. Another individual had illegal drugs. Four of the bikes were stolen. We have two arrests on those bikes and I believe we have warrants in the pipeline for the other two individuals."

Wilson said the majority of the riders came from New York and Maryland and many did not know it was against the law to ride in the streets.

"They were responding to what they saw on social media and they thought they were allowed to be part of the ride out, which of course was illegal," Wilson said.

One man whose vehicle was confiscated spoke to NBC10.

"We all heard about it from the same place, all over the media where everybody else heard it," said the man, who did not want to be identified. "No one actually knew it was illegal. We were just there to show a cause for children."

The man told NBC10 he hopes he can get his bike back so that he can get back to New York.

Both dirt bikes and ATVs are illegal on city streets. For years, police have tried to crack down on city dirt bike riders but are not allowed to pursue them due to a department policy which makes it illegal to chase a vehicle that's only committing a moving violation.

"It's extremely dangerous," Wilson said. "It causes auto accidents. There's always the possibility that we have individuals on the sidewalk that are gonna be hit by these dirt bikes."

Despite the fact that it's illegal, dirt bike and ATV riding in the streets is a popular activity in Philly, especially during the spring and summer months. Wilson still had a warning for riders however.

"When we catch you, we're gonna seize them," Wilson said. "You're not gonna be allowed to get them back."

