bunk. infrastructure maybe - killing Americans, bunk.
Do I smell ozone???
Well emp killing directly doubtful BUT I can think of several devastating and immediate results for such:
Passengers planes in Mid-flight if they were close enough to the EMP would lose electrical Power. If the EMP blows out all the electronics that isn't going to end well.
Shutting down the traffic signal systems would cause some accidents. Hospitals without power would have many deaths due to loss of life support equipment.
So yeah the EMP wouldn't kill them directly but lots of folks would probably die if there was a sudden and massive loss of electrical power, but I doubt Hundreds of Millions would die immediately as a result.