nOmesorah -“Any bystander that wanted to get involved could have killed theses cops in an instant. Like, if the fellow who videoed it would have had a gun.”
Exactly. Being a cop is a dangerous job! You need eyes in the back of your head.
You must take care of the immediate problem – first.
That means taking care of the Guy with the Knife.
Once he’s in a police car & they feel it’s a volatile situation or could become one – sometimes the best thing to do is to leave the Area!