A barbecue at the Lonnie Young Recreation Center in East Germantown turned rowdy on Sunday night when a crowd of roughly 500 teenagers massed there and some of them threw rocks and bottles at police cars.

The recreation center at the corner of Ardleigh Street and East Chelten Avenue hosted a  cookout starting at 6 p.m., similar to a gathering on July 17, which also attracted a police presence. At the earlier event, police made no arrests and the teenage crowd dispersed.

Two juveniles were arrested and charged with disorderly conduct and failure to disperse after Sunday night's disturbance,police said Monday.

Unlike the earlier incident, police helicopters circled tracking the movements of large groups Sunday night.

Sharyn Flanagan, a resident of the neighborhood, said on social media that there were "police choppers, tons of kids, cops chasing ppl down street …they're at it again near #Philadelphia Lonnie Young Rec Ctr."

Police instructed all units to use caution, because "juveniles are now throwing rocks at police," according to a police statement.