Abandoned monster

You and your friends went to an abandoned building one night, following rumors of some kind of creature roaming there, killing every living thing it saw. Eventually, Karl, your first friend, disappeared, but you could hear him screaming heartbreakingly, as if he were being murdered, and he was found dead, and you lost the way to the exit. Only you and Mark remained. You walked together, shining a flashlight, and when it ran out of battery, something quickly grabbed Mark's leg and carried him away, screaming in fear. Ultimately, you were left alone on the 30th floor, alone in the darkness, waiting for dawn while the monster searched for you.