Detectives have launched a murder investigation following the death of a three-month-old baby boy.
A 33-year-old man has been arrested on suspicion of murder in connection with the incident in the Boscombe area of Dorset.
Police received a report on Friday afternoon from the ambulance service that a baby had been injured at a flat on Carysfort Road.
The boy was taken to Royal Bournemouth Hospital before being transferred to Southampton General Hospital for specialist treatment.
Dorset Police said the boy was pronounced dead at 5.10am yesterday.
Detective Inspector Richard Dixey, of the major crime investigation team, said: "I can confirm that the tragic death of this young boy is being treated as suspicious and a murder investigation, led by the major crime investigation team, has been launched as a result.
"A 33-year-old Bournemouth man has been arrested on suspicion of murder and he continues to assist police with their inquiries. Police are not looking for anyone else in connection with this incident."
Scenes of crime officers have examined the Carysfort Road address.
The coroner has been informed and a post mortem examination is due to take place next week.
Mr Dixey added: "I would appeal for the family to be given privacy at this extremely difficult time."