Maybe the gray line is, are you present as a "good samaritan", or are you present as a CERT representative?
I'll give you a couple of real world examples,
During Florence the Newport river flooded. 70 Hwy was blocked to our east by the Newport River and it was blocked to our west by the Neuse River which also flooded. 70 Hwy was under 10 feet of rushing water. Ambulances couldn't take anyone in my area to Caarteret General to our east becuase the bridge was under water and they couldn't take anyone to Carolina East Hospital in New Bern because the brideg was under water. We were literally cut off from the rest of the world. Even the EOC couldn't get fuel for their generators as the tankers could't get here to deliver. Then came the bad weather and the USGC choppers and life flight choppers were grounded. A temporary "medical center" was set up at the Newport VFD but resources were few.
The old guy up the street requires oxygen. He was out. He couldn't get his tank refilled because the roads were all flooded. And even if they weren't nowhere was open in the middle of a Cat 4 hurricane to fill them. Newport Rescue needed their O2 for their firemen emergencies so they didn't have it to spare. However, I had two tanks of 60% oxygen in the garage in the form of two 100 cubic foot steel SCUBA cylinders. I called my boy who is an EMT on the county bus and asked him why couldn't the old man breathe off my SCUBA regulators? He said, "Absolutely. It's all we have. 60% oxygen isn't ideal, but it's better than 20% oxygen. If his O2 meter alarms and displays "low 02" there's nothing that can be done currently. He may die." When I walked into his living room the old man asked, "Did you bring the cavalry?" I said "No Sir. The cavalry can't get here. I'm it." and I rigged up his 02 tube to work off the SCUBA regulator hose with some duct tape. He was able to breathe off those two cylinders for two days until the choppers were no longer grounded and could fly in proper medical oxygen cylinders. See, I was there as a "good Samaritan" and I wasn't representing the County or CERT or EMS. I was just there with a solution to a potentially lethal problem.
The other situation was the people who try to drive thru the water. We had a lady who attempted to drive across the flooded bridge on 70 Hwy. I was there with all my scuba gear in the truck as a "spectator". The Fire Dept was there trying to stop people from crossing the bridge. She either ignored the firemen who were trying to wave her not to try to cross, or maybe she thought they were signaling her to cross, who knows. Her car stalled out once the water got up to her windshield then she was stuck. I told the captain I was a certified Rescue Diver and Master Scuba Diver, had all my gear in the truck, and if they could drive the fire truck out as far as they could, tie me to a rope, I could swim to get her. Then once I had he they could "reel me in" with the winch on the front bumper.
He was reluctant and declined my offer due to floating debris in the water being dangerous. But I suited up anyway. He changed his mind and we did the rescue. Lucky, because the vehicle soon was nearly all underwater when a Interstate Battery truck came up and decided to cross the bridge. He didn't see her car as it was nearly underwater and he rear-ended it and finished pushing it into the river. Lucky for him the big old truck didn't even slow down when he plowed into her Toyota and he was able to back out the way he came once he realized the error of his decision. Again, in that situation, I was "Joe Blow Volunteer", resident of the little podunk town of Newport, and not representing CERT or any other entity.
We also had some of them good old redneck boys motoring around in their jon boats and some of the "Cajun Navy" volunteers rescuing people and delivering them to the makeshift aide station at the VFD. They were simply good samaritans as well, not representative of any agency. The Coast Guard had a crew here with a fast boat but they were stretched thin and usually on another call as you can imagine.
The jist of it all was there was simply no one to call, even if your cell phone worked. No one could get to you. The Sheriffs Dept only had one deep water vehicle and it was constantly on another call as well. Officers no longer responded in patrol cars because it was just wasn't feasable with roads under 3 to 10 feet of water. Choppers were grounded.
Sometimes the old adage applies, "You go to war with the Army you have, not the Army you'd like to have."
~KD3Y