A 19-year-old man and his three young siblings have died after a fire at a bungalow in Lancashire.
The blaze broke out at the house in Lytham Road, Freckleton, at 23:20 GMT on Saturday.
Reece Smith, 19, four-year-old twins Holly and Ella Smith and two-year-old Jordan Smith were taken to hospital but were all later pronounced dead.
Lancashire Fire and Rescue Service said a woman had also been led away from the scene but was not injured.
A police spokesman said detectives were keeping an open mind as to what might have caused the fire.
They are now carrying out a joint investigation with the fire service.
The fire affected bedrooms of the house in the village, which is several miles west of Preston.
From the outside there was no apparent damage caused by the blaze, but the scene has been cordoned off.
Several floral tributes have been left near the house.
Phil Cox, group manager for Lancashire Fire and Rescue Service, said as crews were en route they had 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 firefighters 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.”