Three people were killed when a gunman opened fire inside a Walmart store in Thornton, Colorado, on Wednesday. The police have not taken anyone into custody yet. Soon after the incident, police warned people to stay away from the shopping centre.

Thornton is a suburb about 16 km northeast of Denver. Reports of the shooting came shortly before 6.30 pm local time (6 am IST).

Investigators are talking to witnesses and reviewing the security footage to find information about the attacker, the police said.

“We’ve got multiple parties down, we’re still trying to ascertain what their conditions are,” a police officer told Reuters. He said that customers and staff of the store “self-evacuated” themselves as they fled after the gunfire.

The suspect “nonchalantly” entered the store and opened fire before walking out and driving away in a red four-door hatchback, Thornton Police Department spokesperson Victor Aliva said.

“What we have determined is that it is random as of right now,” Aliva said. “As witnesses stated, the person came in and just shot toward a group.” Aliva added that they are looking for a white man.