NASHVILLE, Tenn. (AP) - A Houston firm specializing in disaster cleanup was picking up debris Monday in the aftermath of a nursing home fire that killed eight patients.

The nursing home was extensively damaged by fire, smoke and water. The cleanup company, Cotton Catastrophe, also has crews working on the East Coast following Hurricane Isabel.

"We're drying out the building and doing debris removal," said Brett Conrad, Cotton Catastrophe's vice president for marketing. "We've got 30 to 40 people on the job, and it will take between three and seven days to complete. The crew is using handcarts and shovels and different drying techniques."

The fire started late Thursday in a second-floor room of the NHC HealthCare Center near downtown Nashville.

Eight patients died, and others were critically injured. Firefighters carried more than 100 residents to safety using backboards and wheelchairs.

Four patients were in critical condition in the burn unit at Vanderbilt University Medical Center on Monday. There were 25 patients at Centennial Medical Center, including five in critical condition.

Baptist Hospital had nine patients in stable condition, including two in the intensive care unit. Two were in fair condition at St. Thomas Hospital.

The cause of the fire is still under investigation.

Fire spokesman Charles Shannon said investigators have narrowed the search down to an area of the room where the bed was.

"That doesn't tell us what started the fire -- it just narrows it to that room," he said. "We'll continue to analyze the bed and other materials at the national lab."

Investigators are examining an electrically powered hospital bed that cranks up and down to allow a patient to sit up to read or watch TV or sleep when lying flat.

Bob Pollard, assistant director of the Fire and Arson division of the Tennessee Fire Marshal's office, said it's uncertain when the U.S. Consumer Product Safety Agency will complete its analysis of the bed.

"We're looking at everything right now," Pollard said. "We've not ruled anything out. The fire was at or near the bed and that's why we want it evaluated."

There is no evidence of arson.

The NHC HealthCare nursing home in Nashville was built in the 1960s and hadn't been extensively renovated, which made it exempt from a 1994 law that required sprinklers.

Fifty-five of Tennessee's 343 licensed nursing homes lack complete sprinkler systems, the Department of Health reported. State lawmakers plan to hold hearings soon to determine how the current law can be strengthened.

Senate Majority Leader Bill Frist, a Tennessee Republican, called on the Government Accounting Office on Monday to look at existing federal rules regarding fire prevention at nursing homes.

NHC HealthCare Corp., the Murfreesboro company that owns the Nashville nursing home where the fire broke out, has self-funded liability insurance -- coverage the company has said may be inadequate in an emergency.

"It is possible that claims against us could exceed our coverage limits and our reserves, which would have a material adverse effect on our financial position," NHC said in a 10-Q statement filed with the Securities and Exchange Commission for the quarter ended March 31.

The company's stock fell 14.9 percent Monday, down $2.81 to close at $16 on the American Stock Exchange. Its 52-week high was $21.30, reached just last week on Sept. 23.

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On the Net:

National HealthCare Corp., http://www.nhccare.com/facilities.htm

Cotton, http://www.cottoncompanies.com/