"At approximately 9:19 this evening, a single male entered the Garden State Plaza mall and fired several shots while the shopping mall was still open. He was dressed in black wearing what is believed to be a motorcycle helmet," Paramus Police Chief Ehrenberg said in a statement.
The shots rang out just before closing time, sending shoppers running for cover. There were no immediate reports of injuries.
"I heard maybe two or three really loud gunshots coming from the Nordstrom section part of the mall, and I just hear people running in one direction just saying, 'There's a shooter, there's a shooter," said witness Nicole Packs.
Police locked down the upscale mall as they scoured the complex for the gunman, who witnesses say was armed with an assault rifle.
"I saw someone walk past my store carrying a large gun, wearing all black," said witness Ally Kozic.
Authorities say so far there's no sign of the suspect or his weapon. They are reviewing the mall's security cameras. Authorities were still searching the mall late Monday night in the event that the shooter is still inside.
"He was a tall guy, but he had a biker helmet, leather jacket, mask, so you couldn't really see his face," said witness Mercedes Hegges. "It was definitely a scary situation."
Paramus Mayor Richard LaBarbiera earlier said there was a "confirmed single shot." Investigators found a single shell casing.