DURHAM, N.C. - Preliminary information indicates a fire at a North Carolina hospital that killed a patient and injured three workers occurred during a defibrillation, authorities said, citing a procedure typically used to deliver an electric shock to the heart.

Spokesman Jim Jones of the state Department of Health and Human Services said the early information shows a spark and a fire took place during the defibrillation early Tuesday at Durham Regional Hospital. In an email sent by his agency, he did not elaborate on the specifics of what happened.

Defibrillation is generally used to re-establish a normal heart rhythm. Fire officials investigating the blaze have not said what caused the fire.

A Durham Regional Hospital spokeswoman said the fire was limited to one room of Select Specialty Hospital, a separately licensed acute care facility that leases space on the hospital's sixth floor and has 30 beds.

The fourth and fifth floors also suffered water damage, authorities said. Twenty-two patients of Select Specialty and about 20 Durham Regional patients were moved to other rooms, said Kellie Peacock, marketing director at Durham Regional.

The fire was reported about 2:15 a.m. When firefighters arrived, the hospital sprinkler system had extinguished the blaze.

Hospital officials were investigating exactly how the fire occurred and just where it began, said Katie Galbraith, Durham Regional's chief of operations.

The patient who died was critically ill, Peacock said. The medical examiner will determine the timing and cause of the patient's death, she added.

Two Select Specialty employees and one employee of Duke University Health System were injured, she said.

The names of the dead and injured were not immediately released.

The hospital was operating normally several hours later. The waiting area showed no sign of the fire. Visitors entered and left, and doctors and other hospital employees went about their business, getting coffee and heading back to their work. A television provided the only background noise.

Karen Baker of Mebane was waiting while her husband underwent an outpatient procedure. She said she initially was worried when she heard that an explosion occurred at the hospital. She called to make sure the hospital was still performing outpatient procedures.

She felt better when she learned it was a fire and that it was limited to the sixth floor.

Durham Regional is a 369-bed acute care hospital.

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Martha Waggoner can be reached at http://twitter.com/mjwaggonernc