The Boulder County Sheriff's Office said it received a call at about 12:30 p.m. Monday about a green sport-utility vehicle leaving a suspicious package that was "partially burned and had wires protruding from it" behind in the Superior store's parking lot, The (Boulder) Daily Camera reported Wednesday.
Deputies said a second call soon came in from a customer who had parked on top of the package and believed it to be a bomb.
The Boulder County Bomb Squad was called to the scene and used a robot to examine the inside of the package.
"It turned out to be a pinata," sheriff's Cmdr. Rick Brough said.
Costco shoppers said the store was placed on lockdown during the incident but was reopened by 2:30 p.m.