It’s also been codified in many jurisdictions.
I do believe, however, that once the police begin to take action, they have an affirmative duty to meet minimum standards of care.
Not really. If they begin to take action, such as begin to suppress a riotous mob, then stop and leave the area, they cannot be held responsible for any damage, injuries or deaths in the area they abandon. Long decided and renewed after the LA Riots in 1992.