Five family members were killed early Tuesday morning when a fire tore through their New Orleans home that had no working smoke alarms, The Times-Picayune reported.

Three children, ages 7 to 11, and their mother died in an upstairs bedroom of the two-story home after the fire started a little after midnight, New Orleans firefighters said. A 77-year-old woman who owned the Broadmoor neighborhood home also died in the flames on the first floor.

The elderly woman's son, Derrick Anderson, who is also the father of the children and their mother's boyfriend, is the sole survivor, authorities told the newspaper.

Anderson was the first one who noticed the downstairs fire when the smoke woke him up. He tried to get his family out of the house but they "wouldn't respond fast enough," said Frederick Anderson, Derrick's brother who was not in the home at the time of the fire.

"My brother, he's in shock," the brother told The Times-Picayune. "I hope he doesn't lose his mind over this, because that was his heart, his family."

Firefighters are not yet sure what caused the deadly blaze which took an hour and fifteen minutes to subdue. Relatives said Anderson's mother, Martha Anderson, was a smoker and that her downstairs bedroom contained an oxygen machine.

The other victims have been identified as 33-year-old Christina Squire and her children- 12-year-old Jade, 11-year-old Jason and 7-year-old Jala.

The siblings all attended a charter school across the street from their Miro Street home, the newspaper reported. Officials from the Broadmoor Charter School Board have started a GoFundMe page to raise donations for the grieving family.

Authorities said the tragedy might have been prevented if the house was equipped with working smoke detectors.

"In my entire career I've never experienced a fire fatality where there were working smoke detectors in the home," Superintendent Timothy McConnell, of the New Orleans Fire Department, told the newspaper. "This is a tragedy of unspeakable proportion, God bless the souls of this family."