I've just tried to drill some small holes (like 3mm) for the screws and rawlplugs for the camera to go in, without success. It's like the bricks are made of cast iron, and the drill won't touch them. I've tried 3 different bits - and it's a 700W mains hammer drill, not some poxy cordless thing
And, studying the bigger hole I made with the SDS drill, I can see what happened - the brick split and fragmented, then the big drill bit jammed between a couple of the fragments, which is why I got smacked on the head.
I've never encountered this before, and over the decades I've drilled a lot of holes in bricks, to put hanging baskets up etc.
Don't know if there are different kinds of brick