QUINCY, Mass. -- There were no smoke detectors in an illegal basement apartment where a father, an infant and a 1-year-old child were killed early Wednesday, fire officials said.

Firefighters were called to the scene of the basement apartment fire in north Quincy early Wednesday that claimed the lives of the three who were living in the house on Robertson Street.

State Fire Marshal Stephen Coan said the apartment was not up to code and it did not have a smoke detector.

"In the particular case of the basement unit, there is no evidence that we could find of any smoke alarms present at the time of the fire," Coan said.

Investigators said while the exact cause of the fire remains under investigation, it appears the fire started near a sofa and is not considered suspicious.

The fire at the six-apartment house broke out before 3 a.m. at 100 Robertson St.

"When you get that call at that time of the morning, you brace yourself," said Quincy Acting Chief Joseph Barron.

The three perished in the fire after getting trapped in the basement, fire officials said.

"It seems the fire had significant headway before we arrived. It was intense for several minutes until we were able to make this one rescue," Quincy Dep. Chief Gary Smith said.

One person, the children's mother, survived the blaze and was taken to Massachusetts General Hospital with serious injuries, the fire chief said. Her husband and two sons were killed.

"We had heavy fire conditions in the basement. We had confirmed entrapment. We went to an all-hands rescue. We were able to remove some victims. Unfortunately, we have three confirmed fatalities and we have one adult in Mass. General at the burn center," Quincy Deputy Chief Jeff Starr said.

Officials have not released the victims' names, but friends identified the man as Audai Hussein, an Iraqi refugee who came to the United States in 1991 and worked at a gas station.

"He was very happy with his family. I saw him last week for the last time," Safah Alnarisi said.

Authorities said another 15 to 20 people lived in the building, but the rest escaped the blaze uninjured.

"It was very hard to see getting out. I never actually saw flames, just a lot of smoke," neighbor Mark Pierce said.

One of the family's neighbors tried banging on their apartment door before he was forced to flee.

"I saw the smoke from the door -- very heavy. So I smacked the door very hard and then called the police," neighbor Mostafa Oubtrou said.

Some residents said they did not hear smoke alarms go off during the fire, they only smelled the smoke and saw the flames. Coan said a hard-wired smoke detector system in the common area of the building had been disabled.

"Unfortunately, that system was dismantled. That alarm system was in the 'off' position, meaning that the circuit breaker that controlled that alarm system had been manually shut off," Coan said.

"My wife had been down there to visit the mom, you know, when she came home from the hospital and she commented that it was very, very warm down there and we wondered if they had a space heater or something to that effect," Pierce said.

Officials said the building only had a permit for four apartments, not six. Quincy Building Commissioner Jay Duca said both the attic and basement units at 100 Robertson St. were illegal.

The owners of the building, Andy Huang and Jinny Xiu Ma, were sent a letter March 10 by the city’s Inspectional Services Department ordering them to stop renting or legalize the attic apartment.

A tenant called Quincy officials to complain that Huang had threatened to turn off his heat and that his attic apartment had no second means of exit, according to a complaint form.

The city was scheduled to inspect the building on Friday.