The Chainsmokers proved once again they know how to throw a party … maybe too well, as their blowout bash for the release of their latest EP got so wild the police had to intervene … TMZ has learned.

Sources with direct knowledge tell TMZ … the duo celebrated their EP ‘Breathe’ with an over-the-top event packed at a private house in the Hollywood Hills Friday night.

Guests, including Corey Gamble, Zack Bia, Carmella Rose, Mike Majlak and more, arrived to find a custom DJ booth, trippy art installations, and signature cocktails inspired by the album’s vibe.

We’re told costumes were the real showstopper though — the crowd included zombie nuns, rogue knights, and even a manic Sasquatch tearing up the dance floor.