Transcript for Wildfires paved the way for this week's deadly mudslides in California
Reporter: Calls of the desperate ringing out. Slogging through two feet of mud, Gower and friends frantically search for his mother Josie. I don't know why she didn't stay upstairs. Reporter: She was here in her home with her boyfriend when horror stroke. The mud just came straight through. It was just -- it just happened too quick. And she couldn't hold on. Reporter: Josie's friend, Doug, has been searching too. You look at disaster, you watch it. Well, you're just watching it. And you're seeing it and feeling it, there's no comparison. No. Oh my god. I can't even imagine Josie, what a horrible experience, oh my god. Reporter: In montecito, California, where mudslides have molded that tortured landscape, already there are 17 reported dead, including Roy router, founder of the St. Augustine's academy. Here comes a flash flood! Reporter: Video of one of the mudslides here. Oh my god, mom! Reporter: Tonight in the Santa Barbara county community, 17 people reported missing. 100 homes completely destroyed. 300 damaged. The only words I can really think of to describe what it looked like, it looked like a World War I battlefield. Reporter: None of the Boulders you see in this field of Boulders was here 12 hours ago. They have literally submerged entire homes. You can see the chimney poking through. It doesn't feel real. Reporter: Last night we found Robert risken searching for his mother, Rebecca. There's clearly no one searching here now. I know they searched the houses, they've been checked, but I don't get the sense that anyone looked downstream. Reporter: Light was fading and his hope was too. You know, it's my mom. I'm fighting with all my heart to find her. But like -- I can't focus too much on -- she's most likely dead out here, you know. Just push my way through. Reporter: He felt there's no option but to keep searching. Just last month, the Thomas fire, the biggest in California history, charred nearby hillsides. Scorching that hillside, burning the trees, shrubs, all the vegetation. Now you have basically a naked hill that has nothing to hold all that dirt and mud in place. When you get rain on top of that, it's going to slide with gravity. Reporter: Today the skies have cleared. But montecito's plight only intensifying. The storm took out montecito's water main. Taps are dry. Power is out. Follow my treads, okay? Reporter: For many here the only option is to evacuate. At the 101 freeway, which was hacked up by debris flows, closed through Monday over a 30-mile section. Montecito is one of the nation's most exclusive neighborhoods filled with multi-million dollar homes. But no one was shielded from the damage here, not even Oprah Winfrey. There used to an fence right here. That's my neighbor's house. Devastated. Reporter: Winfrey also sharing a video of a blazing gas fire and helicopters searching for the missing. Destroyed it looks like several vehicles and that rv there -- Reporter: With the hope of finding those swept away alive dimming, those search and rescue efforts are intense flying. Overnight the coast guard rushing to rescue a family of five. They carefully place the mother and her baby in a basket, then lift a child up to the roof away from that churning sludge. They even managed to save the family dog. In just the past 24 hours, the coast guard has assisted in 29 rescues. 14-year-old Lauren Canton miraculously pulled from a pile of rubble. She was coated in mud but alive. She's now recovering in the hospital. Her father and brother are believed to be missing. And also among the missing, sisters sawyer and Morgan Corey. A cousin of the family posting this photo. Their mother and sawyer's twin sister, summer, currently in the icu. Summer's heart reportedly stopping not once but twice. You can only see the scale of this from the air. This debris field goes down hundreds and hundreds of yards. Almost every house in its path obliterated. And what has made this recovery and rescue so difficult is the thickness of this mud. And right in there is an actual pool. Rescuers have fallen into it. There are so many pitfalls and traps here for them. A pitfall I experienced firsthand. These catastrophic mudslides and flash floods are not without precedent here. In 2005, a mudslide just south of here in la cancita, California, killed ten people. What you see immediately after a mudslide is basically mud that you're able to get through, able to dig out. Over the next few days as it drys out, it's going to become more or less cement. Must have much more difficult to remove. If you think things are ba bad now for people affected by this mudslide, it's only going to get worse the next few days. Reporter: This search and rescue team going house to house, relying on zero's nose to sniff out survivors. Some of the spaces they navigated were so tricky that zero needed a ride. They're taking zero in through the window. Reporter: For hours, some family members like Teresa tried to flag down professional rescuers. Finally she found a sheriff's deputy. He saw her go in, we know she's down there. Reporter: As she continues her search, she comes across Doug Scott, who is still looking for Josie Gower. That's all you can do. Is close your mind off to pain and anguish. Reporter: Josie's son Hayden in anguish over what he says could have been prevented. Voluntary evacuation. If only she was in the mandatory, she would have left. They screwed up. They screwed up big-time. They should have -- they should have said anyone in the floodplain should get the hell out. They should have said something like that. You know? Reporter: Later, Hayden Gower would tell us his mother's body was found. But for those two families, a fleeting respite from their grief with that shared embrace. For "Nightline," I'm Matt Gutman in montecito, California. Up next, a cartel hitman
This transcript has been automatically generated and may not be 100% accurate.