AN investigation is under way after a massive explosion at a chemical plant.

The blast happened at the Terra Nitrogen (UK) Limited site in an industrial area off Haverton Hill Road, Billingham, Teesside, at 12.15am.

Residents reported hearing the huge blast and seeing a massive ball of flame.

The explosion caused a fire involving mixed gases including hydrogen, nitrogen and a small amount of ammonia and prompted the police to declare a major emergency.

Firefighters and ambulance crews were called to the scene and by 2.45am the blaze had been put out.

Two people working at the site were treated for cuts and bruises.

Nearby roads were closed and residents were advised to keep their windows and doors shut as a precaution.

The plant, which produces ammonia and was previously
owned by ICI, was shut down.

The cause of the blast is not clear but police said an investigation would be carried out by the Health and Safety Executive and the Environment Agency.

Joanne Twaits, from Billingham, who said she lived opposite the site in New Road, said: “There was a huge gush of fire and an astonishing thud.

"It woke my two young children and shook the house as I looked out my window.”

Tom Neale in Marske, about 20 miles away, said: “Many people I know said they saw a flash of yellow light.”

Supt Ian Richards of Cleveland Police said the emergency services had the situation under control in a relatively short period of time.

He said: “Fortunately what was initially perceived as a major incident was quickly dealt with.

“The emergency services and petrochemical industry on Teesside regularly exercise to ensure such incidents can be dealt with effectively.

“Their expertise and training to deal with such situations and protect the public is nationally recognised.”

He added that the closed roads had been reopened and that there were no “off-site implications” from the incident.

A Terra Nitrogen UK spokesman said the firm had launched an investigation into the incident which would involve the regulatory authorities.

He said: “The incident happened on a pipe at the plant and led to a fire
involving mixed gases including hydrogen, nitrogen and a small amount of ammonia which was extinguished automatically as the pipe depressurised.

“In line with the plant’s emergency procedures, the county police and fire brigade attended the scene working in partnership with the on-site emergency services. The plant was safely shut down.”

Terra Nitrogen is the UK’s largest manufacturer of nitrogen products used extensively in the chemical industry and agriculture.

The company employs around 400 people in the UK which includes 250 people on Teesside.