End of the world

I have a view of a beach from the sky. The shadow of an alien spaceship creeps across people on the beach and everyone knows the world will end.

I'm running towards a building in a crowd of people; I think everyone is going there to spend the last few minutes of their lives having sex, but another crowd of people is rushing out of the building in the opposite direction. We engage in sort of a reverse tug of war where we try to push the other group back.