The father badly burned in a fatal house fire in Melbourne's west which killed his three-year-old son had posted a snap of himself lying injured in hospital just hours earlier.

Toddler Jordan Dashwood was found dead inside his Werribee home after fire destroyed it in the early hours of Sunday.

The toddler had celebrated his third birthday in February, with father Jeremy Dashwood, 39, paying tribute to his son in a loving post online. 

'Just wanted to wish my big son Jordan Jai Dashwood a massive happy third birthday as he has had the most exciting journey growing into this handsome as, young boy,' he wrote at the time.

'I also wanted to thank all the people who wished my li'l man a happy birthday, all his pressies mummy bought him - it's time for Jordan's cake.'

Mr Dashwood remains in hospital with serious burns after being dragged out of the burning home by firefighters. 

He posted the selfie from a hospital bed the day before the deadly blaze broke out, in which he already appeared to be suffering extensive injuries. 

Covered in bandages, Mr Dashwood simply wrote 'thats ak()' [sic] alongside the image on Facebook. 

Friends and family of the father believed he had been injured after falling off his scooter before the fatal inferno engulfed his home just hours later.

Mr Dashwood had previously posted online that he was 'blessed' to have his kids and family.

It remains unclear how the fire began, with forensic examiners returning to the scene on Monday. 

Emergency services were called to the property on Newbury Street about midnight on Sunday with reports several children were trapped inside.

Victoria Police said firefighters extinguished the blaze, which had fully engulfed the single-storey home, before locating the dead child inside.

Another child, 11, is believed to have escaped the fire by jumping out of a window.

Jordan's grandmother, Tracie Long, identified her grandson as the tragic victim, telling the ABC he was a 'bubbly little boy who was happy all the time'.

Assistant Chief Fire Officer Anthony Pearce said first responders were faced with 'a difficult task', describing the situation as 'a real tragedy'.

'[Country Fire Authority] crews were first on scene and were confronted with a very challenging situation, a very heavily involved house fire, a very chaotic scene,' he said.

Mr Pearce said investigators had not yet been able to determine how the fire started or in which room of the house.

Investigations into the fire are continuing but it is not being treated as suspicious, he added. 

'It's too early to tell, there's a lot of investigation both in the scene and engaging with people to try to understand what's happened,' he said.

'The fire scene is quite dangerous, there's a lot of loose and broken tiles on the roof and it's not a building that's safe to walk through at this stage.'