FDIC has procedures for that type of bank run - company called WDTC has armored semis ready to go, FDIC can ring them up and they can move truckloads of literal cash to banks across the country.

Last time they were activated was in 2008 - supposedly there’s video somewhere.

https://www.wdtc.net/armored.shtml

FDIC’s main responsibility is to avoid bank runs and they have many tools beyond taking banks like WAMU into receivership.