Eh sometimes. depends. Usually on the area and how fast and what capabilities the National Guard and Air Guard have on hand as well as the scale of the event. My unit did Katrina, we had active duty, reserve components from EVERY branch working that one. The big flood of 2008 locally, was Guard and Active duty Marines who happened to be nearby prepping for a deployment. 2012, the big F5 here in Indiana was solely National Guard. the hurricanes last year were a mix of everyone again.