A house fire claimed the life of a 56-year-old man Tuesday in Uptown New Orleans. His sister, who lived with him in the house at 814 Milan St., escaped the blaze safely after being alerted to the fire by a neighbor, authorities said.

State officials said they found a space heater near the origin of the fire, but they had not ruled out other possible causes late Tuesday.

The victim, Mikel Marks, was a “nice, calm kind of guy” who mostly kept to himself, said Cynthia Jackson, a former neighbor.

Firefighters responded shortly before 7 a.m., encountering flames that witnesses described as shooting out of the back portion of the two-story camelback.

Capt. Edwin Holmes, a New Orleans Fire Department spokesman, said both sides of the second floor were engulfed by fire by the time firefighters arrived.

“NOFD personnel received reports that the resident living in the first-floor unit had escaped the building and that there may be a person trapped on the second floor,” Holmes said.

Marks’ body was found severely burned near the front door of the upstairs apartment. He was pronounced dead at the scene.

Holmes said firefighters prevented the blaze from spreading to neighboring homes, though two other apartments in the house received “extensive smoke and water damage.”

Firefighters were still on the scene at 9 a.m. but had put out the fire. A gaping hole could be seen in the roof of the house, which looked to be destroyed.

State, federal and local authorities are investigating.

Brant Thompson, deputy chief of the State Fire Marshal’s Office, said a space heater was found “in close proximity” to the origin of the blaze.

Staff writer John Simerman contributed to this report.