Umberto Lenzi's Nightmare City ( a.k.a. City of the Walking Dead).
It's a great so-bad it's good 1980 horror sci-fi action thriller from Italy/Mexico/Spain and the director of "Cannibal Ferox" Umberto Lenzi about a radioactive spill on a airplane that turns the passengers into fast-moving, running blood-sucking, weapon-weilding radioactive mutant vampire-like zombie creatures that cause mayhem in a big city and can only be defeated if shot in the head.
It's got gore, exploding heads, cool running zombies, nudity, breast violence ( a trademark for Lenzi), action, explosions and anything you wish for in a cool zombie flick, a must see!
Similar movies recommended: " 28 Days Later" ( a movie obvisily inspired by this movie), " Hell of the Living Dead" ( a.k.a. Night of the Zombies, Zombie Creeping Flesh), " Dawn of the Dead ( 1978 and 2004 versions)", " Day of the Dead", "Resident Evil", " Resident Evil Apocalypse", " Lifeforce", " Scanners", " Final Destination 1 & 2", " Night of the Living Dead ( 1968 and 1990)", " The Rock", " Dead Heat ( 1988)", " Die Hard", " Lethal Weapon", " City of the Living Dead ( a.k.a. The Gates of Hell)", " Return of the Living Dead", "Return of the Living Dead part II", "Return of the Living Dead 3", " The Stuff", " Shaun of the Dead" and " The Beyond" ( a.k.a. Seven Doors of Death).