Dozens of police officers from four agencies were called to the mall Friday evening after an initial 911 call.

At least two young adults were taken to hospitals for non-life-threatening injuries, said Monroeville police Chief K. Douglas Cole, and at least two were arrested for fighting from a domestic dispute earlier in the day. He said he expects a number of disorderly conduct citations to be issued as well, although he could not say how many.

The chief said his officers learned later Friday that through social media, hundreds of teens were showing up at the mall, with the influx starting about 4:30 or 5 p.m. and reaching as many as 1,000, according to mall security officers.

“It wasn’t like it was an organized event,” Chief Cole said. Officers will investigate whether the incident was the result of any kind of protest, but the chief said there does not appear to be any evidence of that.

The first 911 call to Allegheny County dispatchers was made at 7:50 p.m., said Amie Downs, a spokeswoman for the county. A second call asking for additional support — which prompted officers from Wilkins, Churchill and the county to respond — was made eight minutes later.

The fights spread, Chief Cole said, as groups of people were running from one side of the mall to the other.

Kyle Edwards, 18, works at the American Eagle store on the mall’s second floor. He was on his break when he saw a fight start on the first floor involving what looked like a teenage girl. Then a male became involved, he said, and “It got bad.”

He saw the fighting moving on the first floor toward Macy’s and then spread up the escalator.

“There were quite a few people fighting,” he said. “I walked back in the store and said, ’This is really bad.’”

Stores nearby American Eagle, including Bath & Body Works and Rue 21, closed, and Mr. Edwards spoke with other employees in his store. They agreed to lock up and told the customers inside they could stay or leave, but they were closing the gate. He estimated about 15 or 20 customers were inside with him.

Mr. Edwards estimated they locked down at 8:05 p.m.

Mall management agreed to close the mall early because the fighting was depleting police resources, Chief Cole said, but by the time everything had shut down, it was close to the normal 9 p.m. closing time.

County police requested additional Port Authority buses run routes from the mall to assist in more quickly dispersing the crowd, the chief said.

There was some minor damage throughout the mall as people were trying to leave — running into things and knocking into kiosks — but nothing substantial, Chief Cole said.