I didn't even know about Eris, but it's a non-exclusive Krewe that second-lines through the French Quarter (without a permit) every Mardi Gras. This year the parade got attacked by the NOPD and there's an ongoing investigation....
Here's a post from the Louisiana Justice Institute that pulled together some of the eyewitness accounts...
One arrestee had a broken cheekbone and a large, matted bloody wound on the back of his head from being beaten with a police baton. Later, this injury would require surgical staples. On the wall where we were kneeling, there was a growing bloodstain behind his head where his injury had bled onto the drywall. "He's bleeding," said another of the arrestees. "Officer, that man needs medical attention."
"I say you could speak? Shut the fuck up," the officer currently watching us replied. A couple of the arrestees had earlier been demanding lawyers, and he had told them to shut the fuck up too. He was big on that phrase...
An officer walked in cradling his hand and smiling. "You need hospital?" The silence-oriented officer asked him.
"Yeah, I'm going in a minute," said the officer with the wounded hand. "I knocked motherfuckers tonight, tell you what."