Four siblings have been killed in a fire at their home after celebrating their mother's birthday.
Reece Smith, 19, four-year-old twins Holly and Ella Smith and Jordan Smith, two, died after a blaze that broke out in their converted bungalow 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 led out of the house by firefighters and was not thought to be injured.
Today her father, Keith Smith, 56, said his daughter, who had been celebrating her birthday yesterday, was staying with relatives in the area.
Mr Smith, who found out about the blaze on the news, said: "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."
Detective Andy Murphy, of Lancashire Constabulary, said: "We are trying to establish the cause of this fire.
"We are keeping an open mind at this stage as to what happened."
He would not confirm the identities of the people who died but said that other people were in the house at the time of the incident.
"We need to determine how many people were there and determine what happened," he said.
He would not comment on whether a party was held at the address last night.
Phil Cox, group manager for Lancashire Fire and Rescue Service, said the service was called to the scene at about 11.20pm last night.
He said that members of the public rang to say that people - including small children - were trapped in the building as three fire engines were en route.
"As soon as the the crews arrived it seemed quite a chaotic scene with a lot of people outside quite distressed," he said.
Six firefighters wearing breathing apparatus rescued the four casualties while another person who did not medical attention was led out, said Mr Cox.
"As soon as they were brought out it was a multi-agency approach to commence resuscitation," he said.
"We would like to pass on our condolences to the family of the victims. It is a tragic situation that we have ended up here today.
"Subsequently there is now a full police and fire investigation to ascertain the cause of the incident and try to piece together what happened last night."
It is thought that some of the casualties were taken from a small room in the upstairs 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 while forensic officers begin their investigations.