A woman has been arrested on suspicion of the murder of her two-year-old son after she walked into a County Durham police station carrying him.
The 39-year-old went to Peterlee police station on Monday morning.
The child, who was not responsive, was taken to hospital where he was confirmed dead shortly after arrival.
Due to his injuries, the woman, from the Castle Eden area, was arrested on suspicion of the boy's murder, police said.
An ambulance was called and the boy was taken to Sunderland Royal Hospital where he was confirmed dead.
A post-mortem examination is due to be carried out later.
A Skoda Octavia car, which was found nearby and was thought to have been the vehicle used by the woman, has been taken for forensic analysis.
Durham Police said the boy was not being named at this stage.