help me find the name of a movie title!

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2 or 3 years ago I seen a horror movie in a DVD store, i didnt buy it however i was intrigued by it. Now i seen an image which reminded me of it and for the life of me i cant remember what the film was called. All i remember was what the front cover looked like, it was a black creature with a round head and no eyes hanging upside down with its mouth open baring its teeth. Im pretty sure the creature was screaming at a man or woman on the cover too.

I remember the film was about a group of people being locked in a building while the power went out and these creatures were hunting them.

please help me find this movie!