Constant reevaluation based on observation. Probably not all the facts are known at this time and they certainly haven't been made public.
Agreed. This is the piece that is often missing in those high profile shoots that don't reflect well on a department.
Officers simply cannot roll up on a scene, assuming they know what is going on, and then try to control the scene and or start using force without taking at least a few seconds to assess what is happening - and then constantly re-assess and keep an open mind as they learn more as things evolve.
That guy trying to get a kid in his car may in fact be the custodial parent getting his kid back from the mom who kidnapped the kid. Yet more often than, not he's likely to be shot or tased if the officers don't slow things down and assess before taking decisive action.