Wedding Party Turns Ugly After Cops Are Called, Mass Chaos

A wedding party in Southern California turned into an all-out brawl with police -- a melee that started with a simple noise complaint ... and the video is wild.

Check out this footage, obtained by TMZ, which we're told shows what occurred after a wedding ceremony at a Quality Inn in Barstow, CA Sunday night, into early Monday morning.

Sources say cops were called over an apparent rowdy group of guests. We're told there was wrestling going down, as a bunch of the guests were MMA trained.

It looks like, when officers arrived, things escalated into violence, with what appears to be one of the cops punching a guy on the ground, who also gets tasered. We're told the cops came upon the group in a common grass area ... and saw 2 guys wrestling. Eyewitnesses tell us the crowd was trying to tell them it was a friendly match, but that the police didn't listen.

We're told the guy who's seen getting punched on camera was zapped 3 times while on the ground. We're told the bride, who is pregnant, was also tased/detained in the mayhem ... and that there were kids present.

Barstow PD tells us the call came in as a report of 4 males fighting in the courtyard, and that a use of force investigation has been opened ... while noting the clip is just a small part of what happened. BPD says the investigation will determine why the officer was punching.