Those struck by gunfire included one of two suspects who were taken into custody, police said.
The gunfire around 5:44 p.m. at the Oakbrook Center mall in Oak Brook, Illinois, sent Christmas shoppers running for cover, police said. An Oak Brook police officer who was working an extra detail at the mall immediately responded, receiving help from other responding officers as well as mall security, according to police.
Investigators recovered two handguns at the scene, police said. In addition, police located a vehicle that was registered to one of the suspects. The identities of the suspects and victims were not immediately released.
Authorities believe the incident started when two armed people and a companion became engaged in a confrontation.
"We believe that two individuals that were known to each other shot at each other, and potentially three would have been struck by gunfire either directly or by ricochet," Oak Brook police Chief James Kruger told FOX 32 of Chicago.
After the gunfire, two suspects ran into the Nordstrom store in an attempt to flee, Kruger said.
The four people wounded by gunfire were taken to a hospital with non-life threatening injuries.
One of the four people wounded was believed to be one of the offenders, Kruger said. Another person of interest was in custody and authorities said a third suspect was at large.
The wounded suspect was shot four times – in the left thigh, right thigh, right calf and lower back, police said.
Two women, both in their 40s, also were shot, both in the left thigh. A woman in her 20s was shot in her right foot, according to authorities.
A fifth person suffered an ankle injury while fleeing the area.
The mall was locked down as police continued to investigate. The scene was declared clear at 11:55 p.m., according to police.
"We have SWAT teams that are going store-to-store in order to clear each store and to make sure that there isn't another possible offender," the chief said.
In a statement, Oak Brook Center thanked the police department "for their diligence in leading this developing investigation."
"Tonight’s isolated incident is extremely upsetting for our shopping center community," the statement said.
The shooting came hours after a suspect and 14-year-old girl were killed in a Burlington Coat Factory in Los Angeles. Officers opened fire on the suspect and the girl was struck by a bullet that pierced a wall and hit her as she was in a dressing room, police said.