(CNN) Search and rescue crews found the body of a 25-year-old woman Saturday morning, raising the death toll from the California mudslides to 19, authorities said.

The body of Morgan Corey of Montecito was found in mud and debris, Santa Barbara County Sheriff Bill Brown said. Her 12-year-old sister, Sawyer , was found dead earlier this week.

Five people are now missing, the sheriff said, and searchers continue to go through damaged and destroyed homes.

Emergency workers on the ground have doubled since Thursday, with about 1,250 trying to find and rescue those still trapped, Santa Barbara County spokeswoman Amber Anderson said.

The mudslides, which came in the early morning hours of Tuesday, destroyed dozens of homes. Those killed ranged in age from 3 to 89, and all lived in Montecito in Santa Barbara County, northwest of Los Angeles, authorities said.

Rescuers have searched frantically for the missing after rivers of mud and boulders flooded through neighborhoods in and near Montecito, an affluent seaside community east of Santa Barbara, demolishing homes and leaving roads impassable.

"In disaster circumstances, there have been many miraculous stories of people lasting many days. We certainly are searching for a miracle right now," Brown said Thursday.

"But realistically we suspect that we are going to continue to have discovery of people who were killed in this incident."

Evacuation zone increased

The immediate areas where people were killed are under mandatory evacuation, and officials increased the size of the evacuation zone Thursday.

"We know that this a terribly inconvenient development, but it is also incredibly necessary," Brown said.

"This entire area is a very active rescue and recovery and repair zone right now," he said.

Photos: Deadly mudslides in Southern California An aerial view of Montecito, California, shows mudflow and debris on Wednesday, January 10, 2018. Heavy rains unleashed deadly mudslides Tuesday that damaged or swept away dozens of homes in Southern California. Hide Caption 1 of 18 Photos: Deadly mudslides in Southern California A damaged home is seen in Montecito on January 10, 2018. Hide Caption 2 of 18 Photos: Deadly mudslides in Southern California Part of a structure sits in a tree after being knocked off its foundation by a Montecito mudslide on January 10, 2018. Hide Caption 3 of 18 Photos: Deadly mudslides in Southern California Emergency personnel carry a woman from a collapsed house after a mudslide in Montecito on January 9, 2018. Hide Caption 4 of 18 Photos: Deadly mudslides in Southern California Kerry Mann navigates the large boulders and mudflow that destroyed her friend's home in Montecito. Hide Caption 5 of 18 Photos: Deadly mudslides in Southern California A view of the 101 freeway from Olive Mill Road in Montecito. Hide Caption 6 of 18 Photos: Deadly mudslides in Southern California Phillip Harnsberger crosses through mud from a flooded creek in Montecito on January 9, 2018. Hide Caption 7 of 18 Photos: Deadly mudslides in Southern California Mud fills the interior of a destroyed car in Burbank on January 9, 2018. Hide Caption 8 of 18 Photos: Deadly mudslides in Southern California Runoff water from a creek floods Highway 101 in Montecito on January 9, 2018. Flooding forced many heavily traveled roads to close. Hide Caption 9 of 18 Photos: Deadly mudslides in Southern California Reilly, a search dog with the Santa Barbara County Fire Department, looks for victims in Montecito on January 9, 2018. Hide Caption 10 of 18 Photos: Deadly mudslides in Southern California A firefighter clears debris in Los Angeles on January 9, 2018. Hide Caption 11 of 18 Photos: Deadly mudslides in Southern California A van is stuck in the mud in the Sun Valley neighborhood of Los Angeles on January 9, 2018. Hide Caption 12 of 18 Photos: Deadly mudslides in Southern California A police vehicle drives across a flooded side road in Montecito, near the San Ysidro exit of Highway 101 on January 9, 2018. Hide Caption 13 of 18 Photos: Deadly mudslides in Southern California Mud covers a road in Burbank on January 9, 2018. Hide Caption 14 of 18 Photos: Deadly mudslides in Southern California Los Angeles firefighters work amid floodwaters and mud on January 9, 2018. Hide Caption 15 of 18 Photos: Deadly mudslides in Southern California A member of the Long Beach search and rescue team looks for survivors in a car in Montecito on January 9, 2018. Hide Caption 16 of 18 Photos: Deadly mudslides in Southern California Mud washes away personal belongings in the Sun Valley neighborhood of Los Angeles on January 9, 2018. Hide Caption 17 of 18 Photos: Deadly mudslides in Southern California Rushing rainwater fills the Los Angeles River near downtown Los Angeles. Hide Caption 18 of 18

He said the zone, which includes areas formerly under voluntary evacuation advisories, would be in effect for one week but that residents should plan for two.

Rescue workers are using helicopters and all-terrain vehicles in a search hampered by blocked roads and downed trees and power lines.

Billy Grokenberger lives in a part of Montecito that was under a voluntary evacuation order. He and his parents put belongings in three cars in case they decided to leave before the storm. They didn't.

"We had thought about leaving, but we had just had the fires," he said, referring to the recent wildfires that stripped the area of needed vegetation. "... We didn't take it serious(ly) enough."

The damage at the chapel at La Casa de Maria in Montecito.

On the morning of the storm, Grokenberger watched as 2 to 3 feet of water streamed down the street.

"(In) four minutes the water was through our wall and in our house, almost to the second story," he said.

"The house is destroyed, but you know, there's just so many others who are less fortunate. But we just feel lucky that we were able to get out and (are) alive."

Risk of mudslides for years

The storm hit hard between 3 and 6 a.m. Tuesday. The rain poured down on hillsides charred by recent wildfires , which burned vegetation that otherwise could make the terrain more resistant to mudslides.

burned more than 281,000 acres in Santa Barbara and Ventura counties from early December into this month. It wasn't fully contained until this week. The Thomas Fire -- the largest wildfire in California's recorded history --burned more than 281,000 acres in Santa Barbara and Ventura counties from early December into this month. It wasn't fully contained until this week.

Geologists and forecasters warned that intense rain could trigger deadly mudslides from the scorched areas.

And because of the fire, communities below the scarred terrain could remain at risk of mudslides for years, said Randall Jibson , a research geologist with the US Geological Survey.

Montecito may be at slightly less risk now, because this week's flooding already brought down vulnerable material.

"(But) no storm brings down everything that is susceptible. There's almost always more" that could come down, Jibson said.

Short term, making the public ready to evacuate during heavy rains is key, he said.

Montecito and Carpinteria are especially vulnerable to mudslides because the steep terrain in some places goes from thousands of feet above sea level to sea level in just a few miles, said Tom Fayram, a deputy public works director with Santa Barbara County.