A man has been arrested after a 20-month-old boy died following a crash involving three cars.
A white Audi, silver Kia Ceed and black Volkswagen Passat collided close to the Holdingham roundabout in Sleaford at around 4.45pm on Wednesday, Lincolnshire Police said.
The young boy suffered life-threatening injuries and was airlifted to hospital following the incident.
He died in hospital at around 1.20am on Friday, the force said.
His family is being supported by specially-trained officers.
The driver of the Volkswagen Passat, a 31-year-old man, was arrested on suspicion of causing serious injury by dangerous driving on Thursday.
He has since been released on bail with investigations into the cause of the collision ongoing, Lincolnshire Police said.
Other people involved in the crash suffered minor injuries.
Anyone who travelled along the A17 between Sleaford and Newark between 4.15pm and 4.45pm on Wednesday, or may have dashcam footage of the incident or the vehicles involved, has been asked to contact the force on 01522 212316, quoting incident 305 of 19 March.
