Gun in Colorado supermarket shooting bought six days earlier

Police tape marks the car park outside the supermarket where the shooting took place (AP/David Zalubowski)

Court documents show a 21-year-old man identified as the suspect who opened fire inside a Colorado supermarket purchased the assault rifle less than a week before the attack that killed 10 people, including a police officer.

Supermarket employees told investigators that Ahmad Al Aliwi Alissa shot an elderly man multiple times outside the Boulder grocery store before going inside, according to the documents.