I'm not LE anymore, but I am the Director of Security at my church. We're located on a busy US highway, with a car dealership, gas station, apartment complex and residential homes surrounding our property.
I've told our folks that our responsibility ends at our property line. If we see something going on in the car dealership, gas station, etc, we be a good neighbor and call 911 to get the police involved.
However, if something spills on to our property, we can get involved and take action, such as locking down the church, or other options depending on the situation. I also stress calling 911 when in doubt.