An 18-year-old has been arrested on suspicion of murder following a house fire in Lancashire which killed four siblings.
Police have also confirmed the blaze was started inside a wardrobe in one of the bedrooms of the house in Lytham Road, Freckleton.
Emergency services were called to the property just before 11.30pm on Saturday, January 7.
Firefighters were able to rescue 36-year-old Michelle Smith but four of her children – Reece, 19, four-year-old twins Holly and Ella, and Jordan, aged two, died later in hospital.
The victims were in two separate attic rooms, which suffered limited fire damage but extensive smoke damage.
The young man in custody is from Lytham and is not a member of the Smith family, Lancashire Police said.
Police at the scene of the house fire in Freckleton
Detective Chief Inspector Neil Esseen said: “We are following a number of lines of enquiry and have spoken to a number of people who were at the house on the night in question.
“However, I would still urge anybody who has any information which they believe could assist us with our investigation to come forward.”
He later added: “At this stage it is still unclear as to what happened in the lead-up to the fire starting.
“This is a tragic incident and our thoughts remain with the family at such a difficult time.
He would not be drawn on whether the suspect was a guest at a party held at the house on Saturday night.
DCI Esseen said it “became clear” once investigators analysed the house that the blaze was not accidental, though he confirmed no accelerant had been used to start it.
:: Anybody with any information about the fire is asked to contact police on 101 or Crimestoppers anonymously on 0800 555 111.