A man and woman have been arrested in England on suspicion of the murder of a 13-week-old baby boy.
The infant was taken to hospital from an address in Velville Court in Newcastle upon Tyne with serious injuries on Friday, and police were told on Monday that he had died.
Inquiries suggested the baby's injuries were not accidental and the death is being treated as murder, Northumbria Police said.
A 34-year-old man and a 30-year-old woman are being questioned.
Police have been out on the streets in the Kingston Park area of the city to offer reassurance as officers carry out their inquiries.
Detective Chief Inspector Mark Ord said: "We know this will shock and sadden the local community and I would like to reassure them we are doing everything we can to establish exactly what happened and how the baby came to suffer such fatal injuries.
"This is a very tragic incident and our thoughts are with all those affected by this sad death."
Anyone with information should contact police on 101 or Crimestoppers on 0800 555 111.