we were able to evacuate two-thirds the other people who stood behind to try to gather their things are now trapped behind the water line. reporter: more than 8,500 people forced to evacuate countywide residents warned not to use tap water. california slammed once again by an atmospheric river life-threatening flash flooding in some places, residents trapped by washed-out roads in others. we re stranded. we re not going anywhere unless it s an emergency. reporter: 4 million people in the west remain under flood alerts with as much as 3 more inches in some places expected through sunday and in the high sierra, another 8 inches to 2 feet of snow is possible the worry there, this tropical system melting part of a historic snowpack, leading to more flash flooding and avalanches in communities already trapped under feet of snow it s kind of like living in a jumanji movie. every da surprise. reporter: in gilroy, california, heartbreak we have nothing left.