The one I’ve been advised to use by a number of attorneys is this:
Other than identifying yourself, “I do not feel well and need medical attention.” Then say nothing else other than to continue to request medical attention or to answer medical questions from the paramedic. You’re going to be coming down from the adrenaline dump so you really aren’t going to be feeling well. You really actually should get checked out by medical professionals - in addition to making sure that you’re not going to keel over from slightly delayed stress, this also will establish an official record of your condition right after the shooting.
Followed by (after being medically cleared) “I am sorry, I will not answer any questions without a lawyer/speaking to my attorney.” Entirely too many people think that this is an admission of guilt and cops will tell you that publicly - but privately, that’s the best way to prevent accidentally talking yourself into a jail sentence on even a righteous shooting.
What most will not tell you...
At the hospital, ask for a tox screen, not charged to your health insurance, but paid for in cash, by you directly.
This is no longer public record, but only available to you...
This will come in handy