In chapter 76, Pulse, we see a parking lot, a street, and (the contents of) a building across the street being taken out by an EMP gun. The target was a computer within the building.
This is weirdly mesmerizing until Randy’s startled out of his reverie by a clunk. He looks over to see that the van he’s blocked in wasn’t abandoned after all; it was full of Dwarves, who have now thrown the back doors open to reveal a nest of cables and wires. A couple of the Dwarves‡ are heaving a boxy apparatus up onto the roof of the van. Cables run out of it to another boxy apparatus down below. The apparatus is electrical in nature – and doesn’t appear capable of firing projectiles – so Randy decides not to pay it much attention for the moment.
(...) Just after he whacks the Enter key to send this command in to Tombstone, he hears an electrical buzzing noise from the van that makes his hair stand on end for a moment. He sees a cop in the video window, frozen. Then the screen of his computer goes blank.
Randy looks over toward the old van. The Dwarves are high-fiving each other.
There is a screeching of tires, and the sound of a low-speed collision, out on the street. About a dozen cars have rolled quietly to a stop, and some have been rear-ended by others that are still functioning. The McDonald’s has gone dark. Television technicians are cursing inside their mobile units. Police officers and lawyers are pounding their walkie-talkies and cellphones against their hands. "Pardon me," Randy says to the Dwarves, "but would you gentlemen like to share anything with me?"
"We just took out the whole building," says one of the Dwarves.
"Took it out, in what sense?"
"Nailed it with a big electromagnetic pulse. Fried every chip within range."
‡ "Dwarves" here, is how Randy classified people earlier in the chapter: "Dwarves (steady, productive, surly) and Elves (brilliant in a more ethereal way). Randy, a Dwarf, has begun to realize that his grandfather may have been an Elf. Avi is a Man with a strong Elvish glow about him. Somewhere in the center of this whole thing, presumably, is Gollum."
Would this actually be possible as described?