A three-year-old boy has died after he was hit by a vehicle as he was out walking with his mother and two siblings.
The incident happened at about 10.35am at the junction of Neasham Road and Falmer Road in Darlington.
The boy was walking with his family, one of whom was in a black pushchair, when they turned into Falmer Road and the collision occurred.
Police have appealed for the driver of a car to come forward as they have not made contact.
A 100-metre cordon was put in place at the scene of the collision as investigations were carried out.
Detective Superintendent Kevin Weir, of Durham Constabulary, said: "This is a tragic incident and we send our heartfelt sympathy to the boy's family.
"We are appealing to members of the public to help us establish the events leading to the collision.
"If anyone witnessed anything on Neasham Road this morning or has any information please contact the police on 101."