Replies

I figured it out. If the entire Presidential line of succession were dead, the House would convene, and by majority vote, elect new Speaker (the old one must be dead), who would become president immediately. They then would elect a third Speaker. If the House could not or did not convene, perhaps because no quorum could be achieved on account of the deaths, the Senate would convene.

If there were no quorum in the Senate on account of the tragic massacre, the Governors so empowered would appoint new Senators from the affected States without delay, and this new Senate would convene. In default of the House, the Senate would debate at length as they always do, call cloture, and select a President Pro Tempore, who, if there still were no President, would immediately become President. The Senate then would need to process the new Presidential appointees.