Complex sentence: Leaving the house, the guests told the family that after some time has passed, behind the front door water will be collected in puddles, and when this happens they should gather the bare necessities, leave their home, and go to the mountains.
Split into simpler sentences: Leaving the house, guests reported that after some time behind the front door will be collected in puddles. And when this happens they should gather the bare necessities, leave their home, and go to the mountains.