NOTE: This story includes information from Halifax Regional Fire that has since been revised. After publication, the fire department updated its findings to say the cause of the fire was smoking materials.

A Lower Sackville, N.S., woman who narrowly escaped a fire that claimed the lives of her husband, son, and granddaughter is speaking out for the first time after investigators zeroed in on an electrical fault as the cause.

Marven Hart, 58, and Carys Whalen, 11, were killed in the fire at 34 Leaside Dr. early Saturday. Trent Hart, 18, was taken off life-support two days later.

"We're not talking about a little fire. We're talking about a fire and carbon [monoxide] poisoning that took out my family and I need that [electrical] work inspected," demanded Pat Hart, 58, the lone survivor.

'Now they're gone'

Despite the devastation of losing three family members, she's demanding to know why a promised wired smoke detector was never installed by her landlord on the second floor of the rented duplex.

"My family obviously wasn't safe that night when they went to bed that night," she said, unable to hold back tears. "Now they're gone."

In older homes, Nova Scotia's Fire Safety Act requires a smoke alarm be installed between the sleeping area of a home and the remainder of the building. But Fire Marshal Fred Jeffers recommends that smoke alarms be installed on every floor and that they be replaced every 10 years.

The Office of the Fire Marshal also noted that there have been 14 fire-related fatalities in the past fiscal year, which began on April 1, 2017.

This week, Halifax fire Chief Ken Stuebing issued a plea for people to make sure there are smoke detectors on every floor and install them near bedrooms.

He said the two-storey Lower Sackville home had just one working smoke alarm. If there had been more, he said, "the outcome might have been different."

Pat Hart says the bond she had with her youngest child, Trent, was 'out of this world.' (Submitted by Pat Hart)

Hart smiles as she thinks about the night before the fire. Trent leaned into his brother, Gary, Carys's father, as they belted out an old country tune, Don't Close Your Eyes.

Carys was upstairs sleeping, so her parents decided to let her sleep and pick her up in the morning, said Hart.

The fire broke out sometime between 1:30 a.m., when Hart went upstairs to bed, and 2:45 a.m. when she woke up to use the bathroom and heard a noise. She thought it was a clock radio alarm, but realized it was the smoke detector on the main floor.

She opened the bedroom door to a house engulfed in smoke.

'It's OK, Pat. I'm here.'

"I went, 'Oh my God, I think we're on fire,'" she said.

She shut the door, banged on the wall to wake up the house, and hollered out to her partner of nearly 20 years.

"Marven said, 'It's OK, Pat, I'm here. I got it.'"

That was the last time she heard his voice.

Pat and Marven Hart were a couple for nearly 20 years and married in 2006. (Submitted by Michelle Barnes)

She crawled to her window, pulled the screen out, yelled for help, and then grabbed her phone and called 911.

"I kept screaming, screaming at the 911 lady on the phone, and she said, 'Ma'am, calm down.'

"'I can't calm down. My family. Please help me, please help me. I can't get out the window.'"

Police officers were the first to arrive on the scene. They found a ladder and rescued Hart.

Firefighters managed to contain the fire to the basement, where Marven's body was found. Carys was upstairs, while Trent was on the main floor at the back of the house, according to city spokesperson Brendan Elliott.

'My heart is shattered'

Hart believes she survived because she was wearing a sleep apnea mask and her bedroom door was closed. She was uninjured in the fire, but was seen by mental health professionals who were concerned about her.

She says she's struggling with feelings of helplessness that she couldn't save her family, even though she herself has a disability and can barely walk as she waits for a knee replacement.

"My heart is shattered," she said. "All I want is them back."

She said she's also angry that an electrical fault is the cause of the fire, which occurred months after a new heat pump, boiler and electrical wiring were installed by an electrician who would be driven to the home by her landlord, Clem Chisholm.

"He did say that he'd done this for years. He was retired," said Hart.

'Why was that smoke detector not ever done?'

She said she's not assigning blame, but wants a thorough investigation because "if there was an electrical fire, something happened that was not right."

The fire at this duplex on Leaside Drive claimed three lives. (Emma Davie/CBC)

She's also enraged that when the work was done last August or early September, a hole was cut in the second-floor ceiling for a wired smoke detector to be installed. The device was never installed.

She said Marven told her he reminded the landlord to install the smoke detector a couple of months ago when he was replacing a bathroom faucet. He was told that the electrician would be back to put in the device, but he never returned, she said.

"Why was that smoke detector not ever done? How could you forget that?" said Hart.

'Why did all three of them have to go?'

She believes that if an upstairs smoke detector had been installed, Carys might have also escaped the fire.

"Why couldn't one of them be saved, just one? Why did all three of them have to go?" she cried.

Carys Whalen would have turned 12 today. (Submitted by Michelle Barnes)

Elliott confirmed investigators found a hole in the ceiling.

In a phone interview with CBC, Chisholm expressed condolences to the family and called the fire tragic, but refused to answer questions about electrical work.

Stuebing, the fire chief, said Monday that evidence showed "an electrical fault as the cause," but added no charges would be laid by the fire or police departments.

Carys would have turned 12 today. Her funeral is Saturday. A joint funeral for Marven and Trent will be held next Tuesday.