A woman has been arrested on suspicion of the murder of a two-year-old boy.
Police were called to a house in Upper Garth Gardens, Guisborough, North Yorkshire, over safety concerns at just gone 10am on Wednesday.
The boy was taken to hospital by ambulance, but medics could not save his life.
Detectives investigating his death arrested the woman, 39, on Friday.
She remains in custody, Cleveland Police said.
Specially trained officers are supporting the family of the boy, whose identity has not yet been confirmed.
Detectives continue to carry out inquiries and officers remain at the property.
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Senior investigating officer Matthew Hollingsworth said: “Officers are supporting the boy’s family and they ask for privacy as they grieve.
“My thoughts, and the thoughts of all those working on this murder investigation, remain with the family.”