Two men and a woman were killed in a shooting inside a suburban Denver Walmart on Wednesday night that forced customers to either hide or flee.

Thornton police reported "multiple parties down" and advised people to stay away from the area as dozens of police cruisers and emergency vehicles raced to the scene.

The men died at the Colorado store, and the woman died at a hospital.

Police spokesman Victor Avila said a man nonchalantly entered the store and fired a handgun into a group of people before fleeing in a car. No one has been arrested.

"This is a very heinous act," Avila said. "We don't know exactly what the motive of the person was, but it was certainly a terrible act."

The spokesman said there is currently no indication that the shooting was an act of terror.