Kaboom. And fireball. And ground shake. And shockwave. And boom. AtomCentral shows us some amazingly clear HD footage restored from 1953 of the Atomic Cannon test from Upshot-Knothole Grable. In the video below, you can see cars, jeeps, buses and tanks against the backdrop of the ginormous blast's initial burst and shockwave. The blast eventually swallows everything.
I'd suggest you watch the video in 1080p HD for the full effect.