Police respond to reports of a shooter at Westfield Garden State Plaza Mall in Paramus, New Jersey
(CNN) -- A shooter opened fire at a New Jersey mall late Monday, sending panic through the shopping center and igniting a massive police response.
The gunman inside Westfield Garden State Plaza Mall in Paramus, New Jersey, has not yet been found during a sweep of the shopping center by Bergen County SWAT, said county Chief of Staff Jeanne Baratta.
The store-by-store sweep is ongoing.
There were no immediate reports of injuries.
At least one gunman is said to have fired shots at security cameras, the state police said.
A single shell casing has been found, a Bergen County emergency management official said.
Eddie Kahmann, who works inside the mall, told CNN he heard 6 or 7 gunshots around 9:20 p.m. ET.
"There was just people running like crazy, so I quickly just closed my doors, ran to the back, turned off all the lights, music and everything, just to stay hidden," he said.
Kahmann spoke from inside the mall, one of the largest shopping centers in the New York City area.
Allie Cozic, another mall employee, said she saw "someone dressed in all black, carrying a large gun, walk past our store."
She said she heard loud bangs about 10 minutes before her store was set to close for the night.
"It was just chaos. Everyone was just kind of running to wherever they could," Cozic said.
"It was almost like when you're watching a horror movie and the killer is walking slowly -- that's what it seemed like. He was wearing all black, it almost looked like body armor of some kind. As soon as I saw the gun, I just turned and ran," she said.
There is a large police presence at the mall, which was set to close at 9:30 p.m. ET. There are about 20 vehicles both marked and unmarked.
Police are putting on flak jackets and bringing out assault weapons. People have been pushed away from the mall and are telling CNN that they've been told the shopping center is on lockdown.
Westfield Garden State Plaza is located some 12 miles from Manhattan. It boasts of being home to nearly 300 specialty shops and boutiques.
CNN's Sarah Aarthun, Susan Candiotti, Scott Garber and Laura Dolan contributed to this report.
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