La Horde / The Horde
"North of Paris. In order to avenge the murder of one of their own by a group of ruthless gangsters, four corrupt cops go on a rampage in a condemned building serving as the mobster’s hideout. Now trapped, the officers are about to be executed when the unimaginable occurs: hordes of bloodthirsty, cannibalistic creatures invade the building, savagely attacking everyone. Unexpected alliances are made when their lives are threatened by the unthinkable."
I've noticed a thing or two about French horror films: they're usually violent and gory as hell, and all kinds of messed up; Frontière(s) for example. The teaser really does make the movie look epic, too. Not sure on the release date yet, but according to IMDb it's scheduled for this year sometime. Here's a couple of movie stills below; nothing special.
Source 1: Arrow in the Head
Source 2: 24framespersecond