They had a legal right to be there according to city law.
When did the City Law grow to the point where killing someone over lawn care became an option? That's my point...
And just why was a "law" passed to give the city that "right"?
Every law ultimately ends with the possibility of lethal actions to enforce it. The folks who say "there otta be a law" had best keep this in mind. Is it worth killing a crazy person because he won't mow his lawn and objects with threats of force to persons ordered onto his property to do that?
Maybe it is. But saying "because it's the law" is not a sufficient justification.
Laws only work because most people will consent to them.