Fall Down Dead

Fall Down Dead is a horrorslasher film released in 2007 starring Dominique Swain and Udo Kier. The storyline involves a metropolitan city in the grip of fear after rolling blackouts bring out a serial killer dubbed The Picasso Killer. One night, in the middle of a blackout, seven strangers trapped in an office building are targeted by the killer as he seeks out the one that knows his true identity.

Source: Wikipedia