Police are responding to reports of a shooter at Westfield Garden State Plaza Mall in Paramus, New Jersey.
At least one gunman is said to have fired shots at security cameras, the state police said late Monday.
There were no immediate reports of injuries.
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.