EAST RUTHERFORD, N.J.  — New Jersey State Police blocking gates outside of a major hip-hop concert at MetLife Stadium had bottles thrown at them by angry people in the crowd who were trying to get inside — some without tickets — and they later used tear gas to try to disperse them, according to officials.

Crowds at the Hot 97 Summer Jam concert became upset Sunday night when the gates were closed and blocked off by police in riot gear. An armored state police vehicle began blasting a piercing loud noise to try to disperse the crowd and police later deployed tear gas.

Additional troops were sent for “crowd control” and arrests were made, a police spokesman, Sgt. Gregory Williams, told The Associated Press. State police didn’t release details about what measures they used to disperse the crowd. The number of arrests wasn’t immediately known.

The disturbance began when crowds of people tried to “illegally” force their way into the sold out event by climbing over fences and forcing their way through security, state police said in a statement Sunday night.

Police said they insisted that everyone outside of the gate leave the stadium complex to avoid congestion when the concert ended.