This is gonna be grim, so just a heads up.
I had this idea as a teenager at the time of the attacks. As horrific as they were, they were especially bad for urban Americans. For weeks after, any time I crossed the Golden Gate Bridge, or walked around the Financial District, I imagined hearing the roar of a passenger jet and looking up in time to see it slam into the buildings overhead.
I thought with envy about the sense of safety that rural Americans must have been feeling, knowing that their community was most likely safe from Al-Qaeda because why would terrorists from the other side of the world bother with the little farming town in Kansas or the mountain village in Idaho?
But then I had this really dark thought - what if they did?
This is the idea that came to mind, reproduced as a POD:
On the night of September 10-11, 2001, a sleeper cell team of 20 Al-Qaeda operatives, many of whom are radicalized Americans, pull up in a dozen or so vehicles on the outskirts of a small town in the Midwest. Under the cover of darkness, they don tactical gear, split up into small teams of 2 or 3, and begin stealthily creeping into the neighborhoods before them.
Over the next three hours, between midnight and 3am, these teams manage to silently break into more than 100 residences. There, they murder everyone they find: parents, kids, elderly, babies, using silenced pistols and bladed weapons. By luck, they catch nearly everyone asleep, and thus no alarm goes out. At 3am, they rendezvous back at the vehicles, pack up their gear, and drive off, scattering on their way to different states.
The next morning, the bulk of the town slowly realizes what happened as phonecalls and door knocks go unanswered. By roughly 9am, the town is swarmed with emergency and law enforcement vehicles, and not long after, the national media arrives. The final death toll: close to 500.
How would the aftermath of an attack like this proceed differently from OTL's 9/11?