Two men have been arrested on suspicion of murder after two people died in a house fire near Middlesbrough.
Cleveland Police said officers were called to a property in the Grangetown area at about 5.20am on Wednesday.
A child is among the two people who were killed in the fire. They have yet to be formally identified.
A 48-year-old woman remains in the Royal Victoria Infirmary (RVI) in a critical condition, and a further three people have suffered non-life-threatening injuries and are receiving treatment in hospital.
Police have arrested two men aged 23 and 31, and they remain in custody.
Investigators are keeping an "open mind and cannot rule out any links to wider organised crime at this time", police said.
A full examination of the scene at Birchington Avenue is still underway.
The blaze occurred about two miles (3km) from the scene of a horror crash on the A66 over the weekend that killed seven people, including two police officers.
Redcar and Cleveland Local Policing Commander, Superintendent Emily Harrison, said: "As we continue to investigate this morning's tragic incident, we continue to support the families of those who have sadly died as a result.
"Our thoughts remain with those families and with everyone involved.
"We continue to work to establish the circumstances of exactly what has happened, but we are keeping an open mind and cannot rule out any links to wider organised crime at this time.
"We will have a high visibility presence in the Grangetown area as this investigation progresses, and to provide reassurance to local communities, who will no doubt be impacted by this tragic incident."
Pictures from the scene show that the roof of one house has been badly burnt and is partially caving in.
Firefighters were seen damping down the smoking roof of the home later on Wednesday.
Cleveland Fire Brigade said they sent six fire engines and the Incident Command Unit to the scene.
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Cleveland Police said the families of the people involved have been informed and are being supported by specially trained officers.
Officers were maintaining a heavy presence around the scene.
Anyone with information concerning the fire has been urged to contact police or Crimestoppers.
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