Volunteers, jail inmates and National Guard troops help residents salvage their belongings Saturday across an area devastated by tornado-bearing thunderstorms that killed at least 20 people, including a teenager struck by a tree as she lay in bed.

President Bush declared four counties disaster areas, freeing federal aid for recovery from the storms that struck Friday, spawning at least one tornado that ripped roofs and walls off homes and threw mobile homes off their foundations.

The twister hit between 3 and 4 a.m., when few people were awake to hear the tornado warnings broadcast just minutes in advance. Few communities in the region have warning sirens.

The storms blew a tree into 17-year-old Brittany May's bedroom, killing her, her stepmother said Saturday.

"We're all in shock. I've lost family members before, and I've never had to bury a child," Lisa May said. "I'm going to speak for her mother, and me and her father: This is the hardest thing that any of us will have to do."

Gov. Charlie Crist toured the battered areas Saturday in Lady Lake, about 50 miles northwest of Orlando.

"Your heart pours out to the people affected and you want to help," the governor said.

Crist was accompanied by David Paulison, director of the Federal Emergency Management Agency, who announced the federal aid.

"It makes you sick to your stomach for what we saw," Paulison said.

Thirteen people had been confirmed dead in the Paisley area plus seven in Lady Lake, about 30 miles to the west, emergency officials said. Among the seven identified Saturday were Brittany, five women ranging from 66 to 81 and a 20-year-old man.

Recovery teams started winding down the search for victims.

"They think they have done the majority of the work in going door to door. It has kind of changed to picking up the pieces today," said Christopher Patton, spokesman for the Lake County Emergency Operations Center.

About 30 low-risk jail inmates from Marion County dressed in green-striped uniforms helped clear debris in Lady Lake. Religious groups helped in the cleanup and some served food to rescue workers and victims, while about 40 National Guard members distributed blankets, food and water.

Lake Mack resident David Demar, 36, who lost his mobile home, said he heard rumors that some of his friends were killed. "The hard part is going to find out who's gone and who's here," he said.

The wind picked up one tractor-trailer rig and slammed it down on top of another one. A church built to withstand a Category 4 hurricane was destroyed.

"To me it sounded like a mountain coming down," said Denise Anderson, 52, who huddled in a bathtub for shelter with her husband.

James Pietro, 42, was sleeping in his RV when the wind and snapping trees woke him just in time to take cover with his girlfriend beneath their bed.

The RV was lifted into the air and rolled several times, coming to a rest a few feet from a pond, upside down and nearly torn in half. The two came away with only scratches.

"I don't see how I lived," Pietro said.

The Volusia County Property Appraisers Office put preliminary damage estimate at $80 million and said as many as 500 properties were damaged.

It was the second-deadliest tornado in state history, behind five twisters in February 1998 that killed 42 people in central Florida and damaged or destroyed about 2,600 homes and businesses.

Jason Pawelczyk, 32, said he and his mother took cover in a closet and emerged seconds later to find half his roof gone.

"We finally made it outside, and all you heard was people screaming for each other," he said. "It was pouring rain, flashlights everywhere. All you could see was silhouettes, people yelling for each other. It was crazy."