“We've got multiple parties down, we're still trying to ascertain what their conditions are,” Officer Victor Avila of the Thornton Police Department said

About an hour after the primary alert, police asserted on Twitter that the threat of firing had ended at the store, which was encircled by police and fire crews.

“At this time this is NOT an active shooter. We will update as info becomes available,” the police department said in that tweet. Affirmation of the two dead came about 20 minutes afterward.

Thornton is city of about 120,000 people approximately 10 miles (16 km) northeast of downtown Denver.

 Victor Avila said police were reached to the store at about 6:30 p.m. Mountain time (8:30 p.m. ET) and that the gunshots had died down by the time the first officers went at the spot.

A Walmart customer, 44 year old, Aaron Stephens, of Thorton, told he was in the interior paying for groceries at a self-checkout stand when he heard gunshots and the sound of bullets.

“The employees started lauding and the customers started shattering” as people began to run away the store, he gave details. “I ran out, too, because I didn't want to get shot.”

Stephens said he did not see where the shooting had come from and did not see anyone hit by bullets.