UPDATE: A crime scene will remain active and investigation open as a forensic officers probe the fierce West St house fire.
While the cause is yet to be determined and a man arrested at the scene, Darling Downs Detective Inspector Dave Isherwood said there was nothing to suggest the fire was an arson attack.
"We're not ruling it out that it's possible but there is no evidence of any human intervention at this stage," Det. Insp. Isherwood said.
"We will probably never know one way or another because of the extent of the damage the fire has caused.
"The investigation has not revealed there was any human intervention."
Det. Insp. Isherwood revealed police had taken several witness statements including an account from the owner-occupiers at the scene, with several lines of inquiry open.
The fire is believed to have started on the northern side of the building and spread quickly through the historic renovated home.
UPDATE: A passing motorist has been hailed a hero after knocking on the front door of a West St home moments before a fire ripped through the historic building.
Queensland Fire and Emergency Services Inspector Peter Bradow said passers-by knocked on the door and helped evacuate a pregnant woman and two others from the property.
They escaped without injury while two firefighters on the building's southern side suffered blisters and heat exhaustion from the blaze which leapt to overhead powerlines and shattered windows on a neighbouring office complex.
Insp. Bradow said 10 fire appliances were at the scene at its peak.
"Crews went into action protecting other buildings around that house (and) at that point, crews have done an extremely good job protecting the building which was in a position of catching on fire itself," he said.
It was a difficult fire to fight, he said, with overhead powerlines posing a threat to the frontline firefighters.
"As the powerlines run directly above us, the crews had to work with those hazards," he said.
"The heat that radiated from there had caught the power pole on fire and the insulators which was then threatening to drop powerlines on the firefighters.
"It created a problem in that it generated a lot of heat."
But the crews managed to isolate the fire and stop it spreading.
"There were two firefighters who fought on the southern side of the building to protect the other structure," Insp. Bradow said.
"They've done an extremely good job - in doing so, they have some minor blisters and heat exhaustion.
"Crews have done an exceptional job. All in all, we had 10 appliances on scene at the peak period trying to control this fire."
Investigations are continuing and a crime scene remains in place around the property.
UPDATE: Witnesses have recalled the harrowing moment they realised a Newtown home was ablaze.
Inside, a woman, believed to be pregnant, reportedly went to the bathroom when the front of the West St home was engulfed in flames.
Nearby resident Jayden Findlay told 7 News the first he knew of the fire was when he heard "a few bangs" about 2am.
"I heard a few bangs and then started to open up my window, heard a few sirens and then a lot of smoke started pouring in," he said.
Queensland Fire and Emergency Services Inspector Peter Bradow said the firefighting effort was intense, with focus given to protecting neighbouring properties and securing the area.
A man was taken into custody at the scene and is currently being questioned by detectives.
A crime scene had been declared around the property.
EARLIER: Fire investigation officers and Toowoomba police are treating an overnight house fire in Toowoomba as suspicious.
A Police Media spokeswoman said fire crews were called to the timber house at West St about 2am.
The fire was well involved when Queensland Fire and Emergency Services arrived at the scene.
The home was destroyed and two nearby properties sustained minor damage to their windows and paint work.
Two women and a man were home at the time the blaze broke out but were able to escape without injury.
Police have arrested one man in relation to the incident who is yet to be charged.
The fire is being treated as suspicious and a crime scene has been established with forensic examination to begin later today.
Investigators are appealing for anyone in the area at the time who may have seen anything suspicious or may have recorded footage of the fire to contact Toowoomba police or call Crime Stoppers on 1800 333 000.
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