For those interested, check into the new program the state of Florida Department of Education has initiated. They are putting an armed and trained SRO into (supposedly) every school. The county sheriffs departments are not longer the primary guardians. I have a contact who is going through the training now and as a former SES with Homeland, he knows what is good or bad. He stated the training is excellent, including three weeks of defensive tactics, 4 weeks of firearms, medical training, virtual reality kill houses, practical range kill houses, bio hazards, learning how to response to gas and structure fires, etc. Hopefully, this program will be adopted by other states.
I understand where you are coming from but, you have to plan the best you can because Murphy will always show up. You may be in battle and the person who is beside of you will have an AD due to adrenaline and shoot the guy next to you( happened to me). Yes, the cop responding may be so jacked up, he/she may shoot the first person they see with a weapon. It is up to dispatch to acquire as much information as possible from the original caller. They must try the best they can under severe circumstances to find out if a friendly is on the scene.
From personal experience, you never go into an armed encounter knowing everything you want to. You simply do the best you can, make the best decisions you can and engage.