Why are the men here?

One of the men says that God sent them to San Francisco to save lives and apparently hers was first. The men tell her that they believe that an earthquake is going to hit in the next four hours. It will be a big one. They say that they prayed about what to do and God told them to tell the people. They tried to get the officials to listen, but they just sent the cops after them. Rae asks the men if they'll come back to help her before the quake hits since she doesn't have a car. They agree to save her and her family.