I'm not quite clear on why this officer was on the porch in the first place. We have a dog who is on its own property approached by a police officer. The dog might have scratched the officer and may also have growled and barked, all normal behaviors for a dog on its own property. These warning behaviors should have been sufficient for the officer to back slowly away and remove himself from the property.
This barking and growling offended the officer so much that he shot the dog sixteen times, enough to require a reloading of his weapon. Even though the dog had backed up into the porch, whining and screaming. Even though there were people inside of the residence. Even though the dog did not actually try to bite the officer.
The dog did die after he suffered several seizures at the veterinarian.