Two terraced houses have been destroyed and another has been damaged close to a bonfire in Belfast's Shankill area.
Firefighters said it looked like the fires at Hopewell Square on Monday night may have been caused by burning embers carried through the air by wind.
Investigations are continuing. Traditional 'eleventh night' bonfires had been lit across Northern Ireland.
The fire service said out of the 123 calls it had received on Monday from 18:00 BST, 42 were bonfire related.
Firefighters had to intervene at 16 of those fires.
A man who lives in one of the houses said his daughter was asleep upstairs in the property when he heard "crackling sounds".
"I heard what sounded like rustling up the stairs," he added. "So I went up into the attic to see what was happening and I saw the smoke."
He said he woke his daughter and then ran next door to help his neighbour.
"The house is destroyed. My bedroom ceiling is bulging like it's about to come in, it's not safe to be in."
Lily Turtle, an elderly woman, and her great-granddaughter lived in the house where the fire started.
A young pregnant woman was among those who lived in another house that was smoke damaged in the blaze.
A woman from Hopewell Square whose house was not damaged in the fire said she had left her home to stay with her sister.
"It was like a volcano erupting," she said. "The sky was red, it was completely red.
"Your life's more important than your possessions.
"I was so angry. When things settled, I thought; 'If my house goes, my possessions, all my kids' and grandkids' stuff, goes with it.'
"It's more upsetting to think that you've worked hard and this happens - it should never have happened.
"It was horrendous - it was like what you see in a movie. The red in the sky, it was horrible."
Alan Walmsley of the Northern Ireland Fire and Rescue Service said crews were at the incident in Hopewell Square "very quickly" and that their "hard work" had prevented a row of terraced houses being destroyed.
He said that the fire service did not believe it was caused by radiated heat from the fire but possibly by burning debris.
"We believe there could have been the potential for hot, burning embers being carried by wind landing on the roof and then making their way down and falling into the roof," he added.
Nathan Gray was watching the bonfire at Hopewell Square and described the scene as "crazy".
"It kicked off about one o'clock in the morning, everyone was watching the bonfire, and the next thing a lot of smoke was coming from the roofs beside it," he said.
"The roofs started smouldering and one of them caved in at about five-past-one.
"People were starting to get moved from their houses - a man climbed through his living room window to get out, it was crazy.
"When we left at about a quarter-to-two it looked like the incident was under control.
"Two firemen climbed up the houses and put ladders to the side to get a better angle to get the hoses out to fight the fire."
Bonfires are traditionally lit in many loyalist areas of Northern Ireland on the 'eleventh night' - the eve of the Twelfth of July.
The fires mark William of Orange's victory over King James II at the Battle of the Boyne in 1690 and supporters say they are an important part of their culture.
The fire service said it had attended bonfire related incidents in Portadown in County Armagh, Ballyhalbert, Bangor, Banbridge and Rathfriland in County Down, Dungannon in County Tyrone and Coleraine, Londonderry and Limavady in County Londonderry.
Earlier on Monday evening, fire crews moved in to dampen buildings next to a bonfire at Cluan Place in east Belfast.
Environmental concerns have been raised about the burning of tyres at several locations where hundreds have appeared.
The Northern Ireland Environment Agency said it has issued five £300 fines over dumping at bonfires within the past two months.