Bomb threats phoned into Mexican casinos last month weren’t related to terrorists or drug cartels, at least, according to one state governor.

Last month, five brick-and-mortar casinos in Monterrey, capital of the Mexican state of Nuevo León, had to be evacuated after 911 operators received multiple phone calls over several days claiming that bombs were set to go off in all five venues.

Hundreds of casino customers were forced to hastily evacuate the venues under orders from management. However, no explosions occurred and subsequent searches of the premises failed to uncover a single explosive device.

No doubt some of the patrons who fled the casinos remembered the horrific attack on Monterrey’s Casino Royale in 2011, in which dozens of gunmen sprayed the venue with automatic fire then doused the floor with gasoline and set it ablaze, resulting in the deaths of 52 individuals. The attackers were reportedly responding to a casino owner’s refusal to pay protection money.