The shooting at The Mills at Jersey Gardens in Elizabeth, New Jersey, less than a half hour southwest of Lower Manhattan, injured one person, police said. The shooter is still unaccounted for.
The mall was evacuated and closed, police said.
"Mall cameras are being reviewed to determine the circumstances of what happened and to possibly identify any suspects," according to Elizabeth police.
The city said in its post that "approximately 25,000 shoppers" had been through the mall since 10 a.m. on Wednesday morning, and the shooting took place just hours before it was set to close Friday night.
"Out of nowhere we just saw people running, screaming and begging to be let into the store," one employee told New York ABC station WABC.
In addition to the New Jersey shootings, a person was shot and killed at a mall in Hoover, Alabama, on Thursday.
Meanwhile, two people were stabbed inside a Macy's at Destiny USA -- the mall formerly known as the Carousel Center -- in Syracuse, New York, on Friday afternoon. Onondaga County officials confirmed both suffered non-life-threatening injuries.
ABC News' Louise Simpson and Jason Volack contributed to this report.