Three people are dead after a fire tore through a one-storey home in Hamilton overnight Thursday.

Neighbours told CTV News Toronto the three were a family; a mother and two children -- a son and daughter -- in their early 20s lived there. Police have not confirmed their identities.

The blaze broke out inside the home on Laird Drive, in the area of Upper Ottawa Street and Limeridge Road, around 12:20 a.m. and quickly spread.

By the time crews first arrived on scene, Hamilton Fire safety officer Claudio Mostacci said there was heavy smoke billowing from the front door.

Firefighters rushed inside and pulled three people from the blaze. One person died on scene, while the two others were transported to hospital where both were later pronounced dead. 

One of them was identified by witnesses as 27-year-old Sammy Khalil.

At that point, Mostacci says that “lifesaving operations immediately began.”

They were all residents of the single-family home, which is part of the city’s social housing portfolio, he added.

No other occupants were inside at the time.

“It is a tragic day here in Hamilton,” Mostacci told CP24. 

The fire was “quickly knocked down," but the cause remains unclear.

“The Office of the Ontario Fire Marshal is on scene and they will be looking at the origin and cause and also whether there was working smoke detectors in place,” Mostacci said.

Neighbours gathered outside the home throughout the day to remember the family. Many described its occupants as caring, nice people.  

 "You know even when I was going through some hard times, they took me in like I was one of their sons and their family," a man, who didn't want to be identified, told CTV News Toronto. 

He explained his friend Khalil was living here with his younger sister, who had been confined to a wheelchair, and mother who was originally from Sudan. 

Others expressed their shock by the flames that ravaged through the home, leaving little but a charred window and air conditioner leading into what appears to be a kitchen.

"It's just too bad that it happened," said Sarah Vas, who lives behind the house. "I mean we didn't actually hear any smoke alarms going off, so I wonder if they were malfunctioning and that was why the family wasn't able to get out in time." 

CityHousing Hamilton's CEO Tom Hunter released a statement this afternoon in which he offered his condolences. He also provided an update on the home's smoke detectors, saying they had been inspected at the beginning of the month and "were operational at the time." 

Investigators are still on scene probing what set off the blaze.