Sexy Women In Costumes Get Into Vicious Catfight At Halloween Party, Watch The Video

A pack of pissed-off party girls turned Halloween into a full-on fright fest... exploding into a wild brawl that triggered a police response.

TMZ got the clip -- and it all popped off outside the restroom at the Unruly Agency/Memehouse Productions bash at CBS Studios Saturday night ... where a pirate-clad partygoer was caught shoving a blonde dressed as Buzz Lightyear, who spun around in shock and snapped, "Bro, what the f**?"

Buzz’s sidekick -- rocking a look inspired by Jessie from Toy story -- then came in swinging, smacking the pirate right in the face... only for the pirate to fire back with some serious, adrenaline-fueled shots of her own.

Honestly, it was pure chaos and dragged on way too long -- and turns out security was nearby the whole time ... finally jumping in to bring an end to the fist fight.

Law enforcement sources tell TMZ ... police got a call from security guards, who were standing with a female victim claiming she was assaulted by three women.

Cops rolled up to the party, but by then everyone involved had already cleared out ... and the victim never pressed charges.