Rochester police say say no one was hurt when rowdy young people gathered while a concert was going on at Ontario Beach Park.
Police had a special events detail at the park last night and saw the number of young people in a nearby pavilion swell to several hundred.
Police closed the park entrances and brought in backup and Pathways to Peace.
After the show ended and the concertgoers left, the young people were seen lighting fireworks and getting into fights.
They were finally dispersed around 10 p.m.