Parvez Hamid says the local community have been left shocked by the tragedy and cannot think of any reason why somebody would attack the family.
"I have no idea why such a thing would happen to such a nice family," said Parvez. "We just can't comprehend.
"Four children and a mother lost at the same time, almost all the family gone, one little child in a critical condition, the father still unwell. Obviously we are all in shock. The whole community is in shock.
"Some of my children went to the same school and they used to play together. They used to come over to our house and my children used to go over to their house.
"I am aware that there are little bits of news over the last few years about burnt out cars and a few little attacks. I just hope this isn't such an attack that has gone ever so badly wrong."
Sabah Usmani, sons Sohaib, 11, and Rayan, six, and 12-year-old daughter Hira, died in their end-of-terrace house in Barn Mead, Harlow, Essex, in the early hours of Monday.
Her husband, Abdul Shakoor, also a doctor, suffered minor injuries as he fought to rescue his family from the blaze.
A third son, Muneeb, nine, and daughter Maheen, three, were rescued by fire crews and taken to hospital in a critical condition but Muneeb later died at the Princess Alexandra Hospital.