The grieving family of slain teenager Angus Beaumont fear they have lost his urn and ashes in a devastating house fire, six years after he was murdered.

Emergency services were called to the Clontarf home of Ben Beaumont and Michelle Liddle, north of Brisbane about 2.15pm Saturday.

Police allege that Corey Wardle, 36, used an accelerant to set fire to the Weaber Street property, where he had reportedly been living with the family.

The fire tore through the property and two other homes.

Wardle allegedly fled the scene but was later arrested and charged with arson (domestic violence).

It's a devastating blow for the Beaumont family, who are still reeling over the senseless stabbing murder of their son Angus in March 2020.

Angus, then 15, died when a knife was thrust 14cm into his chest during a fight with two teens outside McDonalds at Redcliffe.

The older of the killers received a seven-and-a-half year jail term while the younger boy- who inflicted the fatal wound - was handed a nine year sentence.

Both have since been released from prison. 

Mr Beaumont’s sister, Mandy said Saturday's alleged arson had devastated the family.

Her brother also lost his gardening business in the blaze.

'Ben and Michelle have been together for more than 20 years, and Michelle owned the house before that, they’ve been there for forever and that’s where he runs his business from and that’s where Angus and his other brother grew up, and I know it’s just stuff, but it’s also just devastating after the loss of Angus,' Ms Beaumont told the Courier Mail.

'The gardening business has been the one thing that has really kept him going after Angus was killed. 

'If he’s lost his business too that’s just devastating. I don’t know where you go from there. I’m just worried for him and how he’s feeling emotionally.'

Ms Beaumont added that the alleged incident was mental-health related.

She launched a GoFundMe page to 'rally people' to support her brother's family.

'This afternoon his [Ben's] house was (allegedly) burnt to the ground after someone he knew got into his house and poured petrol all over it and lit a match with my brother, his partner and their teenage son in it,' Ms Beaumont wrote.

'They have lost everything. My brother is a gardener and he has now lost all his trucks and his tools too. They have nothing.

'This tragedy is on the back of, in 2020, when my brother's son Angus was murdered in a car park - stabbed to death by two young men who - thanks to the laws in Queensland - both now out and living their lives. 

'This destroyed our family back then, and this next blow is yet another bad thing.

'I am in tears over here, shaking and just am lost to how to fix this.

'I suppose I never can, and this loss is another immeasurable loss to our family. I know Angus' ashes were kept in an urn in the lounge with a big beautiful framed picture of him, and I don't know if they had time to save him.

The GoFundMe had raised $20,000 within 24 hours of the blaze.

The Beaumonts were safely evacuated from the blaze unharmed.

It is understood the family made six calls to triple-0 prior to Saturday's alleged arson incident.

Wardle allegedly fled the scene but was located a short time later by a police dog squad unit with the help of some local children riding their bikes.

Wardle remains in custody to appear in Redcliffe Magistrates Court on Monday 

Police will allege in court that after threatening to kill the Beaumonts, Wardle grabbed petrol from a ute, entered the home, poured the petrol everywhere and set it alight.

Almost 40 firefighters battled the blaze as police made an emergency declaration under the Public Safety Preservation Act due to the smoke levels.

Three houses were already well alight by the time firefighters arrived at the scene.

'With three dwellings each involved in an intense fire, the chance of spread to adjoining properties is very high, so they did a fantastic job to prevent that from happening,' Queensland Fire Superintendent Mark Halverson said.

Up to a dozen neighbours raced to remove lawnmowers and jerry cans of fuel from the Beaumonts' front garden as the home erupted in flames.

'At first I heard the house cracking, and then a few loud bangs,' one man told the Courier Mail.

'Firefighters were here in a couple of minutes and then we all got evacuated.'

A section of Weaber St remained cordoned off with police on guard outside of the affected properties on Sunday.