It's hard to tell the difference, sometimes. Even the commonest of criminals must be able to imagine the possible outcome of Las Vegas's alarms, lights, and police communications going down at once. Rocket science it ain't. They all run on computers. Computers run on electricity.
Computers control the power grid.
Do the math. The equation is simple. The factor to solve for is power. Which brings us to HERF guns. First, be clear that they are not EMP bombs.