JACKSONVILLE, Fla. -- The Jacksonville Fire and Rescue Department responded to a house fire at a duplex on the2200 block of Jadestone Drive.

The Jacksonville Sheriff's Office has not officially identified the man killed in the fire.

A relative of the man who lives in the home said his uncle lived in the house alone.

Investigators with the State Fire Marshal's Office are also investigating the early morning blaze. Foul play is not suspected.

A Mrs. Carter told First Coast News she is the niece of the victim and said her uncle's name is Gregory Caldwell.

Carter said Caldwell is disabled, but did not go into details. Carter also said the family has been told Caldwell was using a space heater when he went to sleep last night. At some point the space heater ignited and possibly exploded, as some neighbors claim to have a heard a loud boom.

Carter said the back of her uncle's home is destroyed and at some point Caldwell woke up and tried to escape the flames. Caldwell crawled through heavy smoke and was found by first respondersnear a fire place inside the home.

Mrs. Carter was arrested when police say she ignored warnings about going beyond the police tape.

Caldwell was a single man in his 40's and leaves behind brothers and sisters.