AN 18-month-old girl who suffered severe burns in a fire which killed her mother, aunt and uncle was last night undergoing emergency skin-graft surgery.

It is believed the baby had been sharing a bed with her mother, and was found by firefighters in her arms.

The blaze broke out in the family's home in Pelham Street, Middlesbrough, in the early hours of Saturday morning.

Despite frantic efforts by firefighters and passers-by, they were unable to save the baby's 27-year-old mother, her 22-year-old sister and 18-year-old brother.

Their mother and her partner managed to escape, and were last night keeping vigil at the Royal Victoria Infirmary, Newcastle, at the side of their grand-daughter.

The youngster suffered 31 per cent burns in the tragedy. A police spokesman said that due to the severity of the fire, it had not yet been possible to formally identify those who died.

Until this was possible, their names would not be released.

Investigations are under way into the cause of the fire, and forensic scientists were yesterday still at the terraced house.

The alarm was raised just after 3.30am by passers-by walking home after a night out, who tried in vain to reach those trapped on the first floor and in a loft bedroom.

The mother and her partner were sleeping on the ground floor.

Two passing police patrol vehicles also made efforts to get through the flames but were beaten back by the intense heat.

Six fire engines attended the scene and firefighters fought to control the blaze.

The baby was discovered with the bodies of the women in the front bedroom, and the teenager was found in the loft bedroom.

Detective Inspector Peter Jones, who is leading the inquiry, said: "This is an appalling tragedy. Three members of a family have died and others have been left badly traumatised.

"The baby girl had been badly burned but surgeons are confident they can take skin grafts from other parts of her body and begin the reconstruction needed.

"This is an incident that has left a close knit community in shock. Several people risked their lives in the early hours of Saturday morning to try to rescue those who died but the intensity of the fire was such that they were beaten back by the flames."

The area around the house was yesterday cordoned off, although flowers had been left at the scene.

Ray Mallon, Mayor of Middlesbrough, visited the scene to pay his respects to the family. He said: "A lady lost her three children and her 18-month-old grand-daughter has been seriously injured.

"It is very difficult to comprehend what she is going through. No words of mine can indicate the trauma this family has gone through and my thoughts and prayers are with them."

Police officers are now trying to piece together the events leading up to the tragedy.