AN investigation is under way after a bullet was fired through the cab of a freight train.

The incident happened sometime after 6.40pm on Tuesday, when the train left Thornaby Depot, Teesside, en route to Boulby Potash Mine, in east Cleveland.

It was not until the return journey, when the driver moved to the cab at the opposite end, that he discovered a bullet hole.

It is believed the bullet passed through the cab window and out the other side. Police are unsure whether the incident was deliberate or accidental, and are keen to ensure it is not repeated.

Detective Chief Inspector Danny Snee said: "We are keeping an open mind. It could be that someone has deliberately taken a shot at the train or someone out shooting or poaching.

"The consequences could have been quite serious. One of the messages we want to get across to people is that we don't want them firing near railway lines."

Anyone with information should contact British Transport Police on 0800 405040