A quick example of a civilian active shooter response bag. This particular bag utilizes a Vertx sling bag with CCW and armor capabilities, and is set up to treat up to three patients in the event of a mass casualty.
Vertx: https://vertx.com/concealed-carry-bags-and-packs (code: prepmed)
Backpack armor: https://premierbodyarmor.com?p=r1MoEO-vq (coupon code: PREPMEDIC)