A murder inquiry was launched by police yesterday after a 21-year-old man and his eight-year-old sister died following a fire at their family home.
Their parents are being treated in hospital for “serious burns” after the early-morning blaze.
Emergency services were called to the fire at a property in Scott Court in Helensburgh, Argyll and Bute, at around 5.10am yesterday.
They found the 21-year-old man dead at the scene.
The other people rescued from the house fire, a 55-year-old man, his 46-year-old wife and their eight-year-old daughter were taken by ambulance to the Royal Alexandra Hospital in Paisley, Renfrewshire.
The young girl died a short time later while her father was later transferred to Glasgow Royal Infirmary, according to the emergency services.
Strathclyde Police have launched a murder investigation.
Area Commander, Chief Inspector Fergus Byrne, said: “Extensive inquiries have been ongoing all day at the scene, including a full crime scene forensic investigation by forensic scientists, fire service and Strathclyde Police. This investigation is continuing, however, we believe that this fire was started intentionally and the deaths are now being treated as murder.”
Streets around Scott Court were cordoned off with police tape and officers were only letting local residents through to their homes.
A police incident support unit and fire truck were parked near the scene and an officer in a white suit was at work collecting forensic evidence.
Police said that post-mortem examinations will be carried out in due course to establish the exact cause of death but that the deaths are being treated as murder.
No details have been released so far by police to give any indication about how the fire started.
The officer in charge of the investigation, Detective Chief Inspector Anne McKerchar said: “This is a tragic event made worse by the fact that it was a deliberate act.”
One neighbour, who did not wish to be named, said: “They had lived there a few years and were a nice normal family.
“It is terrible. It makes any problems the rest of us might have seem insignificant.”