Panic room.
A panic room would have been a lot more convinient for personal safety in those 12 hrs right?
So how will you build yours with the available resources you got.
I'd build mine with a simple 8x8 cinder block wall with a concrete ceiling and an air tight steel door, in the corner of my basement. An air vent with the intake/exhaust being somewhere outside the house, hidden in the garden. With a bed, car battery, water & light snacks, and what ever I could fit in. It can also double as a tornado shelter.
I'm sure, with the Sandin's income, they could have made one a lot better than mine.