The Costco in Pembroke Pines was evacuated Saturday after a grenade was found in the warehouse section, said police.
The parking lot and store, located at 15915 Pines Boulevard, were completely evacuated as the BSO bomb squad was called in and located the package.
Officials said the bomb squad took the pin out of the grenade and said it was a training grenade, not a live one and only used for training purposes.
The store reopened to the public later on Saturday. No one was injured, no arrests have been made and there are no currently no suspects at this time, said police.
Officials said this is an open investigation, but not deemed a "criminal" investigation, because no threats were made.
Police do not know how the grenade got into the store.