It's basically a failure of setting up the proper response playbook.
Instead of:
1. AI detects gun on surveillance
2. Dispatch armed police to location
It should be:
1. AI detects gun on surveillance
2. Human reviews the pictures and verifies the threat
3. Dispatch armed police to location
I think the latter version is likely what already took place in this incident, and it was actually a human that also mistook a bag of Doritos for a gun. But that version of the story is not as interesting, I guess.