The managing director of Darlington auction market has died after he was injured with a captive bolt gun.

The man has been named locally as Stephen Aitken, 45, from Ingelby Barwick, Stockton, Teesside.

Mr Aitken died from head injuries sustained in the incident at 9am on Monday 14 May.

He was taken to James Cook University Hospital, Middlesbrough, but efforts to save him failed and he died at 6pm on Monday evening.

A police spokeswoman said that the death was not being treated as suspicious but circumstances surrounding the incident were the subject of an investigation.

A bolt gun, used to stun animals before slaughter, has been recovered from the scene, the spokeswoman confirmed.

She added that the matter was being passed to the coroner.

John Walton, chairman of the Darlington Auction Mart Company, which owns the site, cancelled Monday’s auction and closed the site for the day because staff were too distressed to work.

Mr Walton told the Northern Echo newspaper: “Everyone is in shock. Our thoughts are with his family.

“I was not present when it happened, but I decided to send everyone home and not hold the market. It was impossible to hold a market – everyone was so upset.”

The market was scheduled for a site move and £17m overhaul despite missing out on a £5m redevelopment grant last year.

The incident at the market at Clifton Road, Darlington, is subject to an investigation by police and the Health and Safety Executive.