Police shot and killed an 18-year-old man Thursday as hundreds of Christmas Eve shoppers hid and were evacuated from a suburban Charlotte, North Carolina, mall, authorities said.

An off-duty Charlotte-Mecklenburg County police officer working security at Northlake Mall, about 8 miles north of downtown Charlotte, responded to gunfire during an altercation among "a group of subjects who have a history of feuding" about 2 p.m. ET, Police Chief Kerr Putney said early Thursday evening.

The officer, identified as Thomas Ferguson, discovered that two people were armed, Putney said. When one of the people pointed a weapon, the officer opened fire, he said. The man, identified as Daquan Antonio Westbrook, was pronounced dead a short time later.

It hadn't been determined whether Westbrook fired back at police, Putney said.

The Mecklenburg Emergency Medical Services Agency said it treated one patient with a leg injury, one patient with an asthma attack and one patient in labor. Novant Health Medical Center in Huntersville told NBC News it treated four people who walked in with injuries related to the incident. It would give no further details.

No officers were injured, police said in a statement at midafternoon. Ferguson was placed on paid administrative leave pending an investigation.

Putney said that the shooting was an isolated incident and that there was never an "active shooter" threat to the general public. There was no evidence that the argument leading up to it was gang-related, he said.

"This is not a random act of violence," he said. "Two parties were beefing back and forth, and it happened to happen at Northlake Mall."

Putney said investigators uncovered "evidence of multiple weapons" at the scene near Dick's Sporting Goods on the lower level of the mall.

Witnesses told NBC station WCNC that they heard about a dozen shots.

"All I heard was just gunshots back to back, and literally everyone just flooded in the store saying, 'shooter, shooter, shooter,'" Sarah Ward, who works at Bath and Body Works, told WCNC.

Her first thought, she said, was: "Am I going to die?"

Donald Campbell, who was shopping at the mall at the time, told the station: "I just think it is crazy what is going on here."