Earlier quoted context omitted.
Perhaps this is too political, but the only tool they actually needed was one they had the whole time. Charge the offices based upon the evidence and open a more detailed investigation. The military equipment was entirely unnecessary - but it's very availability makes opportunity for bad decisions.
In all probability, union rules stand in the way of making any quick arrests. Their hands are tied. It is better for them to appear slow and do things by the book than try to appease the irrational mob. They'll eventually get to where the mob wants to go rather than ending up with the cops "winning" in some way due violations of union rules and procedures.
That’s what the riots are about after all; I don’t think anyone needs it to move quickly, they just need acknowledgement justice is needed and will meaningfully move forward. There was previously no promise of that.