I have written a story almost exaclty like that!! Did I steal it from you? How dare me~!
Except mine starts in a crowded park where suddenly people start staring at their cell phones as odd messages start coming in, and suddenly all around everything starts going bonkers (street lights malfunction leading to car crashes, lights on buildings all going off)
It turns out some programmer accidentally flips the default value on one little bit, on one little boolean variable, in one little piece of internet communications protocal software from false to true, which makes it echo and repeat every command given before sending it on.
The leads to an immediate and exponential doubling of internet traffic in microseconds, as messages are replied to answer original messages which are then replied back to the answering messages, and so on, that brings down everything connected to the internet.
And everythig is connected to the internet, so everything stops.
For reasons that become evident later in the story, I wanted to focus on why this one narrator survived. I even had the grid go down while he was asleep in a motel on a road trip. But I find your description of folks’ moment-by-moment reactions to be extremely interesting. One of the goals with my new story is to encourage writers in other fields to explore their own ideas of how it might unravel. I’d love to get the guesses of nuclear plant engineers, police officers, nurses, etc. Hour by hour as the grid falters and dies.
Something similar to that happened in the early days of ARPAnet, before al-Gore invented it.
Once it’s size increased to a certain “critical mass”, it at one point, before it got reeled-in, was strangled by auto-replies to auto-replies to auto-replies...