Let the police escalate up to skip shots with shotguns if necessary to quell riots. Anything beyond that should be handled by the National Guard.
On the other hand, some equipment has both a military and a law enforcement use. Grenade launchers for example; some types of armored vehicles; many forms of personal protective gear.
And the separation of enforcing the law and keeping normal civic order, vs. suppressing riot and civil insurrection, will require that the military receive special training and equipment: some less lethal weapons and ammunitions; special urban warfare/riot control vehicles; personal protection gear (shields, body armor, etc.); street warfare tactics and fighting techniques, including a lot more hand-to-hand combat training both armed and unarmed. And the military personnel will have to learn some law enforcement theory and practice as well: how to recognize when a civil crime is being committed; how to record and preserve evidence; how to make an arrest; how to cooperate with and support local law enforcement, so they, the Guardsmen, don't have to become cops, but can leave that to LEO.
It won't be easy, but it would be better than policemen becoming soldiers.