Witness call after Northumberland train crash
Police say witnesses are crucial to establishing how a car crashed on to a rail line before it was hit by a train badly injuring a boy of 11.
A Range Rover carrying a mother and her two sons came off the A69 and ended up on the railway line near Greenhead, Northumberland, on Wednesday afternoon.
The 11-year-old boy is critically ill in hospital.
Northumbria Police said one line of inquiry was that another vehicle had been involved before the train crash.
Police said the Range Rover was travelling west on the A69 when it crashed on to the Newcastle-Carlisle railway line and received "a blow from a train".
The boy was airlifted to the Royal Victoria Infirmary in Newcastle. His mother was also taken to hospital with minor injuries.
Earlier, Northumbria Police said they believed having spoken to witnesses that a vehicle may have left the scene and they were initially treating it as a hit and run road traffic collision.
They have now said that is one of the lines of inquiry.
Det Insp Peter Reeve, from Northumbria Police said: "I am not ruling anything in, I am not ruling anything out. We have got an open mind in relation to this."
He urged anyone who was in the area at the time to contact police.
British Transport Police said the freight train remained upright and on the tracks.
The Rail Accident Investigation Branch has been informed.
Northern Rail said all lines between Carlisle and Hexham were blocked following the crash on Wednesday afternoon but services were running normally on Thursday.