A police spokesman said the volunteers, trained in line searches, were expected to meet with police first thing Wednesday morning at the Everton Hills address to help search the area.

Police were investigating the 24 hours leading up to the suspicious fire and have called for witnesses or anyone with dashcam footage from the area to contact Crime Stoppers immediately.

“We are now in the process of ... conducting further investigations to establish what exactly took place over the course of this morning and in fact the last 24 hours of events that people may or may not have seen within this street or within this area,” Detective Acting Inspector Joe Zitny told media on Tuesday afternoon.

“I seek the assistance of the community for any people that may have noticed anything or saw something remarkable, or something out of place or something different in the vicinity.”

Emergency services were in the process of retrieving the bodies from the Everton Hills address on Tuesday afternoon after neighbours heard yelling and an explosion about 5.40am.

Fire crews were called to the home, where neighbours have since reported smelling fuel and seeing flames bursting through the roof, double the height of the two-storey house.

QFES Inspector Steven Bates said the building was badly burnt and fire crews had to stablise some of the floorboards to give police access to certain rooms.

Police and forensic teams were expected to remain at the crime scene for a number of days.

From her home across the street, Rowena Ostrofski heard what sounded like something heavy being dropped on the ground, large enough to vibrate the floor, and a woman shouting “help”.

Inspector Daniel Bragg said the fire was being treated as suspicious.

"It was a loud explosion, quite significant, and the neighbour that heard that explosion contacted the police," he told reporters near the Pavonia Street home.

"I'm told that the fire could be seen from a fair distance away and it was the flames and the smoke that actually led people to the address."

He said one neighbour had told police that there was "some yelling beforehand" and confirmed police were looking into multiple reports that one or more vehicles were heard driving away from the home but said no evidence had been found to back that up.

"At this stage, we do not know what happened here. A very thorough investigation will be conducted into this."

Inspector Bragg said all options were being explored in relation to the cause of the blaze.

“The fact that we’ve got three deceased persons inside a house with a house fire, particularly adults, would obviously lend a lot of weight that we’d treat it as deliberately lit,” he said.

“We’re not saying it is, we don’t know, but we will treat it as deliberately lit until otherwise.”

Ms Ostrofski’s husband, Lindsay, said there were vicious flames underneath the house and the whole thing went up “within a matter of seconds”.

“I hear glass breaking so I went to the kitchen and check it,” Ms Ostrofski said.

“Then I hear a woman’s voice saying ‘help, help' and then I look at the bigger window and I saw the smoke on the roof.”

Luke Demnar said he was one of the first on the scene after seeing flames from the top of the nearby hill as he arrived home from dropping his wife in the city.

“(I’ve) run up through the house to see if we can find anyone,” he said.

“We couldn’t get in because the flames were too big.

“(We) pretty much looked in through the doors. The whole house was just engulfed, there was no way we could get in, at all.

“The only place that wasn’t engulfed in flames was the garage and we had a look through there and everything looked normal. We couldn’t see anyone or anything like that.”

Mark Dumont, whose neighbouring house was damaged slightly in the fire, said he thought the explosions were caused by the fire, rather than the other way around.

"It was huge. All the upper level was engulfed. The explosions, all the glass was going everywhere," he said.

After six crews battled the blaze for about 40 minutes in the morning, fire investigators spent the rest of the day determining what happened.

Superintendent Bevan Moore said firefighters had to force their way into the building, which was made more difficult because the fire was burning through the roof.

“Reports from neighbours have indicated that there were unusual noises associated with the fire and so there has been reports that we need to do further investigations to determine the cause,” he said.

“There were explosions reported by neighbours, the smell of fuel, things like that.”

Another man, Nathan Wynne, heard the explosion from his home on neighbouring Lily Street and rushed down to help.

He said he heard a road bike "just roar away" after the "boom" of the explosions.

Carol Maior said her husband, Doug, heard two cars driving away at speed, after two explosions, a small one followed by a bigger one.

"When you see something like that you hope everyone got out but it’s sad to hear there was people passing away," she said.

Neither Inspector Moore nor Inspector Bragg would comment on where the deceased were found or where the fire appeared to have started.

Police were yet to formally identify the victims but multiple neighbours said they thought a woman and her adult son had lived there for about two years and kept to themselves.

Several neighbouring properties were evacuated as firefighters fought successfully fought to stop the intense blaze from spreading.

Inspector Moore said video of the fire showed flames likely twice the height of the house.

-with Amy Mitchell-Whittingdon