THORNTON, Colo. – Police have arrested the suspect in a deadly shooting at a Thornton Walmart store.

Scott Ostrem, 47, was taken into custody Thursday morning at 72nd and Federal.

Witnesses told Thornton Police that Ostrem "nonchalantly" walked into the store Wednesday night, took out a handgun and began firing randomly at people. Two men and a woman were killed.

"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."

IMAGES | Photos capture chaotic scene after Thornton Walmart shooting

Police originally reported "multiple parties are down" after they were called around 6 p.m. to the store located at 9901 Grant Street in Thornton. The store was evacuated as authorities arrived on scene.

Police found the victims in the south entrance. The two men were pronounced dead at the scene. The female victim was transported to Denver Health where she later succumbed to her injuries. Authorities have yet to identify the victims.

No other physical injuries were reported. However, police say several people received medical attention for anxiety. Several distraught employees could be seen in the parking lot comforting each other.

Investigators say there is no indication that terrorism was a motive, but have not ruled anything out at this point. They are still interviewing hundreds of witnesses and going through surveillance video.

Special agents with the Bureau of Alcohol, Tobacco, Firearms and Explosives were helping police in the investigation.

The shooting at the busy shopping center forced customers to either hide in the store or frantically run for the doors.

Witness Harold Stevens said he was in the store with his son when he heard at least three shots. He said an employee directed him and his son to a back door where they were able to escape safely.