The Bloomington Police Department tweeted shortly after 8:15 p.m. that police and emergency medical crews were on the scene of a shooting at the mall. The lockdown lasted for about an hour before the mall tweeted that shoppers were being sent outside.

Police did not immediately provide details on whether anyone was injured or arrested.

Videos posted on social media show shoppers hiding in stores, and an announcement in the mall warned people to seek shelter. Some videos show shoppers running for cover after a loud bang is heard. Emergency vehicles converged in the snowy parking lot outside, and police could be seen putting up yellow crime scene tape near the Nordstrom store.

The reported shooting comes as shopping centers and malls across the U.S. see an influx of customers just days before Christmas.

Jenny Hefty of Sioux Falls, South Dakota, and her 16-year-old daughter had just gotten off the escalator up to the mall’s second floor, right in front of the Nordstrom store, when people started running toward them and screaming. Her daughter thought she heard gunshots, although Hefty did not.

“At first we thought they were just messing around,” she told The Associated Press on Friday night. “It was like ‘why are all these kids running by us?’”

Retailers began shutting their doors and her husband told them to run as armed guards rushed toward Nordstrom, where Hefty had been trying perfume about 20 minutes earlier.

The trio raced to their hotel in the mall complex and frantically tried to reach the couple’s 18-year-old daughter, 21-year-old son and their friends on their cellphones. They had been shut inside stores or whisked into safer spots as the mall locked down.

The family, which often travels the four hours to the mall, was in town for the Minnesota Vikings football game against the New York Giants on Saturday.

“Of course we wanted to come early and do some Christmas shopping,” Hefty said.

Since it opened in 1992, the mall has been the largest in the U.S. and is a tourist destination and community gathering spot. It bans guns on the premises but does not have metal detectors at its entrances.

The mall was placed on lockdown in August after a reported shooting at the suburban Minneapolis shopping complex sent some shoppers running for cover and two people were wounded last New Year’s Eve during an apparent altercation.

Representatives from the city of Bloomington and the Mall of America did not immediately return requests for comment.