PEOPLE who knew "happy, friendly" five-year-old Jason Baillie have told of their sadness at his death.

Jason suffered 90 per cent burns in a house fire on Tuesday and had been cared for in Newcastle General Hospital.

Jason, from Thornaby, near Stockton, died on Thursday night.

His grandmother, Susan Baillie, who was 40, was pronounced dead at the scene of the fire, in Havelock Street, on Tuesday night.

Firefighters battled intense heat to rescue Jason. He was treated in the intensive care ward in Newcastle, where his mother, 22-year-year-old Joanne Baillie, held a bedside vigil.

Joanne received treatment for burns and smoke inhalation after she escaped the fire through an upstairs window.

Paul Thompson, 47, also escaped by jumping from the window, and remains in the James Cook University Hospital, in Middlesbrough. He had burns and leg injuries, but they are not thought to be life-threatening.

Messages for Jason have been left at the scene of the fire, some by children. One said: "Thinking of you, Jason."

One neighbour said Jason could often be seen playing in the street and was a "normal, healthy child".

After news of Jason's death was announced, Ann Tebbutt, the acting headmistress at his school, Harwood Infants, said all the children and staff were deeply upset.

She said: "Jason was a happy, friendly boy and he will be missed very much by all the children and staff at the school."

Tributes have also been paid to Susan Baillie, who was well-known in the area and was described by one woman as "a kind of mother to all the children on the street. She was always one to keep an eye on the children".

Investigations by police, the fire brigade and forensic experts are continuing, although police said the fire was not being treated as suspicious.

It is thought the blaze, which started before 5pm, began downstairs and spread, trapping the family upstairs.

Witnesses said the fire was so intense that windows smashed and flames lit the street.