Police have revealed a father "fought hard" in a bid to try and save his family from a house fire at their Essex home, which claimed the lives of his wife and four children.
Dr Abdul Shakoor suffered minor injuries in the blaze, but his wife Sabah Usmani, who is also a doctor, sons Sohaib, 11, and Rayyan, six, as well as 12-year-old daughter Hira, died in their end-of-terrace house in Barn Mead, Harlow, Essex, at about 1am.
A third son, Muneeb, nine, and daughter Maheen, three, were rescued by fire crews and taken to hospital in critical condition, although Muneeb later died at the Princess Alexandra Hospital.
Dr Shakoor is suffering from the affects of severe smoke inhalation and remains in hospital. Officers from Essex Police say he is "distraught" and, despite his injuries, he is "desperate" to help the police investigation.
The family members died after their home in the Barn Mead area of Harlow was engulfed by flames in a suspected arson attack on Monday.
A car parked near the house was also set ablaze in what police described as "arson".
Assistant Chief Constable Gary Beautridge said: "In the history of Essex Police, seldom has there been an incident of this gravity, in which five people, four of them children, have lost their lives...I would like to stress that the father of these children was in the property at the time and fought hard to save his family in appalling conditions."
ITV News reporter Lewis Vaughan-Jones reports:
He added: "With the tragic nature of this incident at the forefront of our minds, I pledge to use whatever resources are necessary to find out exactly what has happened and, if appropriate, bring those responsible to justice.
"To that end I can tell you that we have launched a Major Crime Investigation to determine the facts surrounding this tragedy and would appeal for anyone with information to make contact with us."
Fire crews were called to the home at 1.45am, where they found a house "well alight" with flames pouring from the building.
Chief fire officer David Johnson said the fire developed rapidly, suggesting some kind of fuel may have been used.
Police said a nearby car fire was being treated as arson, but the vehicle was not connected to the family involved in the house fire.
Neighbour Sharon Pavey said the family had recently moved to the area and the father worked as a doctor.
"I don't think many people knew them but we are all in shock and this is very sad news," she said.