Police have captured a man who shot dead three people at a Walmart store in suburban Denver.

Two men died after the gunman opened fire inside the store in Thornton, Colorado, on Wednesday night.

A woman was also injured, but died later in hospital.

Scott Ostrem, 47, was taken into custody a day after the shooting following a tip-off from the public.

He was detained after a "quick pursuit" in the suburb of Westminster.


Police said they did not yet have a motive for the attack and that Ostrem had "a minimal criminal history".

Officer Victor Avila said police were called at around 6.30pm local time on Wednesday and that the gunshots had ended by the time emergency services arrived at the scene.

"What we have determined is that it is random as of right now," Mr Avila told reporters.

"As witnesses stated, the person came in and just shot towards a group."

Aaron Stephens, 44, a customer at the store, said he was paying for groceries when he heard gunshots and the sound of ricocheting bullets.

"The employees started screaming and the customers started screaming. I ran out, too, because I didn't want to get shot," he said.

Ostrem will appear in Adams County District Court on Friday (3 November).