FORT DODGE, Iowa — Fort Dodge police are working to figure out if a threat made at Walmart is credible. Police confirm a picture was posted on social media, showing a threat written on a bathroom stall. The threat says they will “shoot it up tomorrow” (with Tuesday’s date). It also said “good luck” and included vulgarity. Investigators are working to find out who wrote the message. They have extra patrols at the store.