Here is a really great looking teaser trailer from the people who brought us Frontière(s). Horde is being described as a cops and robbers plus zombies film.

Synopsis:

North of Paris. In order to avenge the murder of one of their own by a group of ruthless gangsters, corrupt cops four 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.