Officials detonated the devices safely early Saturday, and no one was injured. Additional detail on the devices was not available.
The discovery was made at the Colorado Mills Mall in Golden, Colo., after police responded to a report of a break-in. The Jefferson County Bomb Squad detonated the devices. Damage to the store was minimal.
Police made no arrests, but the FBI is investigating.
The mall opened as usual Saturday, though the bookstore was shuttered.