Essex police have said the answers to the house fire that killed five people "could lie in the local community".
They said Dr Abdul Shakour, the father and husband of the deceased, fought to save his family's lives in appalling conditions.
He is now being treated for smoke inhalation at the Princess Alexandra Hospitalb- where he is employed - and, while he is in severe shock, he is desperate to support the police investigation.
Dr Sabah Usmani, and her three sons, Sohaib, 13, Muneeb, 9, and Rayan, 6, and her daughter Hira,13, all died following the blaze.
Dr Shakour's three-year-old daughter Maheen is currently in hospital and has been described as "very poorly". She was transferred to a specialist burns unit at Broomfield hospital in Chelmsford earlier today.
The Muslim family moved to Harlow in 2011. They moved to the UK from Pakistan in 2009 and Dr Shakour works at the hospital where he is now being treated.
The police said there is no evidence to suggest this was a racist attack and that they have not yet determined what caused the fire or if it had been started deliberately.
They were keen to stress that they are at the very early stages of the investigation and are treating it as an isolated incident. Scientists are currently on the scene gathering forensic evidence.
Detective superintendent Rob Vinson added: "For the sake of the family, who are trying to come to terms with this tragic incident, I would ask for information from the public, especially in the Harlow area, to help us determine exactly what has happened."