A father died trying to save his daughter in a house fire police believe was started deliberately.
A murder inquiry has been launched after the deaths of Andrew Broadhead, 42, and his eight-year-old daughter Kiera in Wakefield, West Yorkshire.
A 35-year-old woman and girl, aged 13, escaped the blaze through a bedroom window at the house in Ash Crescent, Stanley, in the early hours of Wednesday.
Both were treated in hospital but have since been discharged.
Police said they believed Broadhead managed to get out of the house but returned in an attempt to save Kiera.
Detective Chief Inspector Nicola Bryar of West Yorkshire Police said a substance may have been poured through the letterbox, and the person responsible may have been burned in the process.
She appealed for anyone with information to contact the force.
At a press conference on Thursday, Bryar said: "This is a terrible incident which has robbed a family of a husband and their youngest daughter. Following inquiries, we are now treating it as a murder inquiry.
"The seat of the fire appears to have been by the front door and we are investigating the possibility that an accelerant was poured through the letter box.
"We know that this fire took hold extremely quickly and it is possible that the person who set this fire was themselves burned in doing so.
"Have you seen anyone with burns or burn injuries in the last 24 hours in circumstances which you found suspicious? If so, then please contact us as a matter of urgency."
A JustGiving page set up to support the family has raised more than £5,000.