Chaos erupted Sunday night outside an urban music concert in East Rutherford, New Jersey, where Chris Brown and rappers Big Sean and Kendrick Lamar were set to perform.
Group fights broke out, bottles were thrown, and other disturbances were reported outside the venue, according to CBS 2 New York.
Police in riot gear descended on the stadium and fired tear gas to control the crowds at the Summer Jam concert sponsored by New York’s Hot 97 radio station.
One state trooper was injured, according to local media reports, though the extent of his injuries was not known.
The stadium was placed on temporary lockdown, and an armored tank emitting a high-pitched whistle was brought in to disperse hundreds of spectators from the parking lot.
Multiple arrests were made.
Fans including filmmaker Nimi Hendrix posted photos of police in riot gear on their social media accounts.
Chart-topping singer Brown also posted an Instagram photo of himself on stage.