A woman killed in a house fire has been described by her mother as "a beautiful soul, who would have done anything for anybody".
Natalie McDonald, 34, died along with her seven-year-old niece, Valentina Foster, in the blaze in Grangetown, near Middlesbrough, in the early hours of Wednesday.
Cleveland Police said the fire had also left a 48-year-old woman in a critical condition in hospital alongside another three people who suffered non-life threatening injuries.
Two men, aged 23 and 31, had been arrested on suspicion of murder and were in police custody, the force said.
Lisa Kirton, Natalie's mother, told the BBC her daughter was "lovely, bright and bubbly" and "everybody loved her".
She said Valentina, also known as Tina, had been spending the summer holidays with the family.
"She was a cute little kid," Kirton said. "I can't believe it, seven years old - it's just a disgrace."
She also said Natalie's 15-year-old daughter and a friend had managed to escape through an upstairs window.
The friend, she said, had "kicked out a window" and "had saved their lives".
A 20-year-old neighbour told the BBC how local residents had tried to rescue the occupants.
Ellie, who did not want to give her surname, said: "The entire house was scorching.
"I couldn't get near the front of the house, it was that hot."
She described holding the hand of a crying woman who had jumped from an upstairs window, staying with her until paramedics arrived.
A neighbour, who asked not to be named, said: "My daughter heard shouting and screaming this morning. The dogs were barking."
On Wednesday, Police officers guarded a cordon around the scene and Northern Powergrid staff were also on site.
Cleveland Fire Brigade said it had sent six fire engines and the Incident Command Unit.
At 13:30 BST it confirmed the fire had been extinguished, but one engine remained on "proactive standby".
A spokesperson said road closures were in place and asked members of the public to avoid the area where possible.
They also said the "tragic incident" was being jointly investigated by the fire service and Cleveland Police.
Cleveland Police said it was "keeping an open mind and cannot rule out any links to wider organised crime at this time".
The fire happened about two miles from the A66 crash that killed five young men and two police officers on Saturday morning.
Redcar and Cleveland Local Policing Commander Supt Emily Harrison said the force was working to "establish the circumstances of exactly what has happened".
"We will have a high visibility presence in the Grangetown area and encourage anyone who has concerns, or who may have information, to approach our officers."
Patrols had been increased in the local area to "reassure the local community", the force said earlier.
Grangetown councillor Adam Brook urged people not to speculate or share unconfirmed information.
Redcar MP Anna Turley said the community had faced a "profound amount of heartbreak over the past few weeks" and expressed her condolences to the loved ones of those who died and were injured.
The families of the people involved have been informed and are being supported by specialist officers.
