New York - Riot police were hastily called in and officers used mace when a major hip-hop concert in New Jersey erupted into violence on Sunday, US media and authorities said.
Trouble flared and arrests were made at Summer Jam at MetLife Stadium when crowds without tickets attempted to storm the venue, police said.
Police used mace to attempt to control the agitated crowd, CNN reported.
Video and photos posted on Twitter showed police using shields to protect themselves as they were pelted with objects and several terrified concert-goers could be seen fleeing from the chaotic scene.
Kendrick Lamar and Chris Brown were among the artists performing at the concert.
"This evening, security personnel at one of the entrance gates to MetLife Stadium were confronted by crowds attempting to illegally enter the sold out Summer Jam concert by climbing over fences and forcing their way through security personnel," New Jersey State Police said on Facebook.
"The gates have been shut and troopers on site have called for assistance from several nearby stations to help maintain order."