War of the Worlds

When astronomers detect a transmission from another galaxy, it is definitive proof of intelligent extra-terrestrial life. The world's population waits for further contact with bated breath. They do not have to wait long. Within days, mankind is all but wiped out by a devastating attack; pockets of humanity are left in an eerily deserted world. As aliens hunt and kill those left alive, the survivors ask a burning question - who are these attackers and why are they hell-bent on our destruction?