If people on the presidental line of succession died

I know that when there's something like a state of the union address going on, one person or so on the list is secluded somewhere and everyone else is present. But...what would happen if someone knew where everyone was and just killed them all? What...

would happen next?

I love American government and history and I'm working on a paper and this question just popped up in my mind...sorry if it's random.

In most circumstances, if something huge like that is happening, they will separate ell of the important people. And hide at least some of them =)

Well... since it hasn't happened yet, I guess their preventative measures are working pretty well.

It's a lot of people:
Vice President, Speaker of the House, President Pro Tempore of the Senate,
Secretary of State, Secretary of the Treasury, Secretary of Defense,
Attorney General, Secretary of the Interior, Secretary of Agriculture,
Secretary of Commerce, Secretary of Labor, Secretary of Health and Human Services,
Secretary of Housing and Urban Development, Secretary of Transportation, Secretary of Energy,
Secretary of Education, Secretary of Veterans Affairs, Secretary of Homeland Security

Wiki addresses your question without providing an answer (because there is none) in the "Theories regarding exhaustion of the list" section of the below link.
http://en.wikipedia.org/wiki/United_States_presidential_line_of_succession

You should watch the movie "Eagle Eye"
I think you would really like it,

Yep - Pelosi 2 heartbeats from President.

I know what the line of succession is. I was just curious as to what would happen if they all somehow died and congress couldn't get together to pick a pro tempore or house speaker. Eagle Eye was awesome!