A man and three children have died after a blaze in a bungalow, police said.
The fire broke out at the detached house in Lytham Road, Freckleton, Lancashire at 11.30pm yesterday.
The four victims were taken to Preston Royal Infirmary but were all later pronounced dead.
Their mother Michelle Smith, 36, who has five other children, was lead out of the house by firefighters and was not thought to be injured.
Today her father, Keith Smith, 56, said his daughter was staying with relatives in the area.
Mr Smith named the victims as Reece Smith, 19, four-year-old twins Holly and Ella Smith and Jordan Smith, two.
Arriving at the scene, Mr Smith said: "I found out about it on the news and heard there had been a fire at a house in Lytham Road and I started to think it might be Michelle and the kids.
"It's very shocking, these are such tragic circumstances.
"I don't know anything about what happened last night. They have lived here for about two and a half years - this was their grandmother's former home.
"I haven't had chance to speak to Michelle yet. It is just terrible.
"I last saw them all just after Christmas.
"I can't think of any reason why this has happened. It has just come as a big shock."
Mr Smith said his daughter Michelle had celebrated her 36th birthday yesterday.
Phil Cox, group manager for Lancashire Fire and Rescue Service, said the service was called to the scene at about 11.20pm last night.
As crews were en route, they received calls saying people were trapped inside the property, including a number of small children.
"As soon as the the crews arrived it seemed quite a chaotic scene with a lot of people outside quite distressed," he said.
"We sent in six fire fighters who rescued four people and also led out one other person.
"We had police officers, fire officers and paramedics at the scene working on resuscitating the people brought out before they were taken to hospital.
"We would like to pass on our condolences to the family.
"There was a reasonable amount of smoke at the time, we were faced with quite a heavy smoke-logged building."
He said forensic teams are now in attendance as police and fire services commence a joint investigation into the cause of the fire.
It is thought that some of the casualties were taken from a small attic-room at the rear of the converted bungalow.
At the front of the property there was no apparent damage caused by the blaze and the scene was cordoned off.
A number floral tributes had been left outside.
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