Is violating the Constitution a criminal offense? These officers violated the law in service of the State, as agents of the State, not for personal gain or motive.

It's not at all clear that the officers are the criminals here, and not their chief, their mayor, their governor. Holding the system/state accountable is a complicated question. Civil suits are a relatively flexible tool.

When you look at police shootings, for example, we pursue criminal charges when the officers show personal malice or "hate crime", not when they shoot in accordance with their training and the department's overall use-of-force principles. It's hard to show that it's correct to throw individual officers in jail for following the will of "the People overall" and the local Executive.