I wonder if this was some scheme to shoplift? Surely nobody was searched as they were evacuated from the building, and mixed in with the masses, someone might be able to walk off with something in a bag or beneath clothing after their friend calls the store with the threat.

I say so because something similar occurred at a company I worked for. A boyfriend of a worker would call in a bomb threat there from time to time, forcing a evacuation so his girlfriend could leave early and be with him. The authorities grew suspicious since bomb-scare calls mainly came in on Fridays, and they eventually caught him.