Friends of a mother and her four children killed in a suspected arson attack have paid tribute to a "beautiful, well-behaved family".

The family, named by friends as Sabah Usmani and her sons Sohaib, 11, and Rayan, six, as well as 13-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.

Meheen remains in a critical condition and has been transferred to a specialist burns unit at the Broomfield hospital.

A man - thought to be the children's father, Abdul Shakour - has been treated for minor injuries. It is understood he was inside the house when the blaze started but had escaped by the time firefighters arrived. He is not currently being treated as a suspect, police said.

Parvez Hamid, 43, and Safia Anwar, 38, have known the couple since they moved to the area. The family are originally from Karachi, Pakistan, but had lived for more than a decade in Saudi Arabia before moving to Manchester and later Harlow.

Both parents were doctors. Abdul Shakour worked at the Princess Alexandra Hospital while Mrs Usmani cared for the children.

Mrs Anwar said: "They were a wonderful family. The children were best friends with our own. We would seem them at mosque and at the school gates. They were just such a lovely family. I last saw Sabah on Friday. She seemed normal with no worries at all. I heard what happened from a friend who lived nearby. It has come as such a shock to us all and it is still sinking in. We are absolutely devastated."

Mr Hamid said: "There children were so well behaved and I was always envious that mine weren't the same. They were hardworking parents who will be missed. The Asian community is very tight knit in this area and we are all in shock."

Senior investigating officer Detective Superintendent Rob Vinson said: "This is still the early stages of our investigation into the tragic deaths of five members of one family - a mother and four of her young children. At this time we are investigating to see whether this fire was started deliberately and need anyone with information to contact us."