The dead children were three-year-old twins and two other children aged six and nine.

The BBC's James Shaw reports from the scene

The children's father was also killed in the blaze which broke out on the top floor of a tenement flat in Tower Crescent, Renfrew.

Ambulance officials said that three children, aged three, six and nine, were taken to hospital but were dead on arrival. Another three-year-old died at the scene.

Police say another girl, a ten-year-old was rescued from the flat and taken to the Royal Alexandra Hospital in Paisley in a critical condition.

Two women, thought to be the mother and grandmother of the children, were taken to hospital suffering from shock and smoke inhalation.

A Scottish Ambulance Service spokesman said: "It is very traumatic for the crews, and a tragedy for the family."

Malcolm Ward of Strathclyde Fire Brigade gives details of the rescue bid

The fire service had tried to rescue the family. Assistant Firemaster John Martin said: "We were told by neighbours and the children's mother that people were still in the flat when we arrived.

"Six officers attempted a rescue but the smoke logging was particularly bad.

"They found four child casualties and removed them. Three of them subsequently died in hospital.

"One child was rescued and taken to hospital but she is giving us cause for concern at the moment. We believe the fire started in the back bedroom."

Another officer described as the fire as a "blazing inferno".

"When we got to the scene the heat was very intense and the smoke was extremely thick," said Assistant Firemaster Rab Coke.

"We have some idea how it started but we are still investigating", he added.

He also said the council had recently fitted smoke alarms in the homes, but could not confirm whether one was in use.

Neighbour Agnes McAdam, 38, who lives on the ground floor of the tenement, was devastated by the fire.

"I rushed out just after six o'clock after hearing shouting that there was a fire up the stair," she said.

"We ran out onto the street and smoke was pouring out of the window. We couldn't get in to the flat by ourselves. The firefighters were on the scene very quickly but couldn't save the children. It's a terrible tragedy."