The American Civil Liberties Union of New Jersey is calling for an investigation into police tactics outside a hip hop concert at MetLife Stadium.

State troopers used pepper spray, tear gas and noise generators to disperse crowds who police say were trying to get into the Hot 97 Summer Jam without tickets. Sixty-one people were arrested at the event in East Rutherford, N.J. 

“Whenever tear gas is used, whenever sound cannons are used, whenever riot gear is used in a civilian context, civil liberties are put at risk and a closer look is required,” said Udi Ofer with the ACLU of New Jersey. He wants the state attorney general to investigate “whether the tactics enforced by state troopers and police were appropriate.”

The attorney general's Office did not immediately respond to our request for comment.

New Jersey State Police said in a statement that Sunday's crowd at the annual concert was unusually disorderly.

Police say trash and bottles were thrown and 11 state troopers sustained minor injuries.

“A small group of highly disruptive people ruined this concert for many others," said Colonel Rick Fuentes, Superintendent of the New Jersey State Police. "They created a danger to ticket-holders, stadium employees, and troopers on the scene. Our troopers took the appropriate steps to restore order to what was a brief and volatile situation."