JACKSONVILLE, Fla. -

A man is dead after an early morning fire at a duplex in the Sandalwood area, according to Jacksonville Fire-Rescue.

Shortly after 4 a.m. Friday, JFRD and the Jacksonville Sheriff's Office responded to the fire at 2200 Jadestone Drive. Firefighters found a man unconscious in the living room. The victim was pulled outside but could not be revived.

Fatal fire scene The victim's name has not been released, but a relative who arrived at the scene was so upset and lashing out that she was arrested for breaching the peace and resisting arrest without violence.

IMAGES: Fatal fire

The fire was quickly extinguished, but about 50 percent of the building was damaged, JFRD spokesman Tom Francis said. The adjoining duplex, which was unoccupied, suffered smoke damage.

Remnants of a space heater, other electrical equipment and candles were found where the fire started on an enclosed back porch of the home.

"As of right now, we don't have any reason to feel that this fire is suspicious," said Detective Andy Redding, of the State Fire Marshal's office.

Jessica Christian said she came outside when she heard the sirens and was sad to learn her neighbor had died in the fire.

"I feel sorry for his family," Christian said.

The family spent most of Friday morning going through the house, trying to salvage what they could.

While it wasn't yet conclusive that a space heater was involved in this fire, authorities took the opportunity to remind people they can be dangerous.

"This weekend we're going to have some substantially cold temperatures, and keeping in mind with the effects of space heaters, keeping them too close to their items, like couches and stuff like that," Redding said.