Four workers have been taken to hospital after a leak at a tanker firm - which saw emergency services at the scene and a company investigating the serious incident.

Emergency services from the fire brigade and ambulance service were called to Suttons Tankers, on Preston Farm Industrial Estate near Eaglescliffe at around 9am on Monday (January 16) after reports of a leak. 

Two fire engines attended the scene, while ambulances and paramedics were put on standby.

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The firm said the 'unexpected leak' happened at around 9am when there was a 'release of product into the atmosphere' at the Stockton depot.

It was stopped at around 10.20am, but four people were taken to hospital as a 'precautionary measure'.

Sutton Tankers confirmed it is launching a full internal investigation and is co-operating with the authorities.

A spokesperson for the tanker company said: "We can regrettably confirm that earlier this morning at around 9am there has been a release of product into the atmosphere from an unexpected leak in our Stockton depot. The leak has now been stopped and the incident has been contained.

"As this incident has just occurred, the cause of it is currently unknown. However, we are launching a full internal investigation and are cooperating with the relevant authorities.

"There were two technicians in our on-site workshop at the time and four people have been taken to hospital as a precautionary measure.

"We can confirm that the emergency services have departed, the site is now back open operationally and all staff have returned to work.

"Safety is a key focus for Suttons and is one of our core values. We take safety very seriously and all our staff are trained to the highest levels."

A section of the site was taped off by the fire service to prevent access before it was later lifted.

A spokesperson for the North East Ambulance Service said: "We were called at 8.45am to persons unwell at an industrial site in Preston Farm Industrial Estate.

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"We dispatched two double-crewed ambulances, one vehicle from our Hazardous Area Response Team, a clinical team leader and were supported by a doctor from the Great North Air Ambulance. Two patients were taken to North Tees Hospital."

A spokesperson for Cleveland Fire Brigade said: "We were called on just before 9am to an incident on Preston Farm Industrial Estate. Two fire engines in attendance from Thornaby.

"There was a small leak contained to the site and dealt with by site personnel. NEAS were in attendance and fire brigade crews were on protective stand-by. We received the stop at 10.22am."