I don't think the officials would really want to admit publicly that they're responsible for forcing them into the clash. It's ancedotial, though playergamer said that he saw it on livestream.
edit: Are you SURE 'proper procedure' is to force them into conflict?
... are you sure it's not?
Gods fuck but I'd like to think it wasn't, but this is also american police. Given the extent it's been noted white supremacists and similar shitheels have infiltrated our body of officers, even if it wasn't proper procedure it could have been entirely too goddamn intentional on their part anyway.
Probably "just" gross incompetence, to the extent the cops are to be blamed for anything that's happened today,* though. That and your standard degrees of concern when one of the groups involved are white and right-wing, anyway.
* Which is only so much, for what fairness is to be given. End of the day it wasn't them that decided to commit domestic terrorism/vehicular homicide, this time. Or beat people with lit torches. All the other shit.