A fire at a Metairie apartment building that killed three people and left nearly a dozen others homeless early Tuesday morning has been deemed a case of arson because of evidence that an accelerant was used to make it spread more rapidly, state Fire Marshal Butch Browning said.

The two-alarm fire that raced through the building at 2308 Harvard Ave. was reported about 2:45 a.m.

Forty-five firefighters extinguished it a short time later, but the flames gutted one unit and damaged several others, displacing 11 people.

One man, who authorities said was the registered tenant of the apartment that suffered the worst damage and where the three people died, was injured when he escaped by jumping out a second-story window.

Browning said Tuesday afternoon that while the investigation was still in its early stages, the blaze was determined to have been intentionally set in a stairwell of the apartment building. Any accidental causes were ruled out, he said.

The Jefferson Parish Sheriff’s Office crime lab will investigate evidence from the scene to determine what accelerant might have been used, he said.

“We have a very cumbersome investigation going with the Sheriff’s Office and Fire Department,” Browning said.

Whoever is responsible for the fire will face charges of arson and possibly homicide, he said.

Col. John Fortunato, a Sheriff’s Office spokesman, identified the victims only as a woman believed to be in her early 40s, a man in his early 30s and another man in his late 50s.

Nearby resident James Norwood said he didn’t know anything was wrong until he was awakened by someone banging on his door and shouting, “Fire, fire, fire.”

He went outside to find other residents trying to make their way to safety through a thick fog of smoke that blanketed the neighborhood.

“It was blazing,” said Norwood, 66, who lives in a building next to the one that burned. “That fire was shooting 30, 40 feet in the air.”

Although his building did not burn, the heat from the flames damaged one of its exterior walls.

By daybreak, there was little for burned-out residents to do but try to salvage what they could.

Geraldine Norman had just moved her furniture into a first-floor apartment and was preparing to move in, she said.

She had recently installed an alarm system that alerted her to the fire through a phone call. She said she rushed to the scene, not knowing what she would find.

Daylight revealed a badly burned structure, with the most severe damage apparently done to the second floor, where the flames devoured the roof.

The charred remains of Norman’s unit suggested that most of the belongings she had moved in were destroyed, but she was hopeful a few pieces might be salvageable.

Norman said she will stay with her daughter while she searches for a new home and tries to replace her property.

“At least I wasn’t in there. Thank God for that,” she said as officials made their way through the building to look for evidence.

The 11 who found themselves homeless after the fire were being assisted by the American Red Cross, which was helping them locate emergency housing and providing help with food and clothing, said Melissa Eugene-Duplantier, a spokeswoman for the local chapter.

Mark Bone, the Jefferson Parish coroner’s chief investigator, said the identities of the victims remained unknown Tuesday afternoon and that causes of death had not been determined, pending toxicology tests.

Fortunato said the 44-year-old man who jumped from the window was in the same unit as the three people who perished in the fire.

That man told investigators he and the victims ran to a bedroom after finding smoke and fire at the front door and in the staircase that leads to the unit, Fortunato said.

The surviving man said he jumped out the window to escape the fire and thought the others would follow him.

“They were good people,” Will Stone, who knew the victims, told WWL-TV. “I’m very messed up because of it.”

Anyone with information about the fire is asked to contact the Fire Marshal’s Office at lasfm.org/ars_hottip.htm or (866) 946-1097. Tips can be submitted anonymously.

Follow Danny Monteverde on Twitter, @DCMonteverde.