4:25 PM PT -- A representative for Katt Williams tells TMZ ... the show was actually only cut off about five minutes early -- so, the Indianapolis audience didn't miss too much of the show.

We're also told Katt's team believes it's the venue's policy to turn on the lights as the show's ending ... and not directly related to the brawl.

Katt Williams' recent show didn't end with a standing ovation ... instead, it finished with bloody fans exiting the building -- 'cause a brawl apparently halted the set.

The comedian/actor hit the stage at the Indiana Farmers Coliseum in Indianapolis Saturday night ... but, it seems about partway through the stand-up, a fight broke out in the stands, and it brought everything to a stop.

Check out the vid ... it's hard to tell, but it certainly looks like there's some movement in the upper regions of the arena as well as a lot of shouting and confusion.

A man with a flashlight -- possibly security -- sprints toward the section in the clip while tons of onlookers shout and scream from down below.

The lights flip on, but by then many people are already rushing toward the exit ... with most of the violent action seemingly wrapped up.

It clearly was pretty violent too ... 'cause another angle of the people up top shows one man's face totally covered in a red substance looking surprisingly like blood.

BTW ... it seems they evacuated the entire venue -- 'cause several people posted TikTok vids outside the stadium lamenting their fun night ending early.

As for what Katt did during all this ... totally unclear. We've reached out to Williams and his team, but haven't heard back just yet.

We've also reached out to the Indianapolis Metropolitan Police Department ... so far, no word back.