Four people have been taken to hospital after a chemical leak at a water treatment plant in Teesside.
Emergency services were called to the Biochemica UK plant in Cowpen Lane Industrial Estate in Billingham at about 11.25am on Friday (2 September) to reports of a chemical reaction from a tank or tanker.
Four workers suffered breathing difficulties when some of the chemicals reacted with each other and formed a small gas cloud.
The North East Ambulance Service sent two ambulances and two hazardous area response teams to the scene before taking the patients to North Tees University Hospital in Stockton.
John Fraser, head of operations at Biochemica UK, said the workers are not thought to be in a serious conditions and were taken to hospital as a precaution.
"The people involved were doing a routine bulk delivery," he told the Teesside Gazette. "This is something we do every week.
"There was a reaction within the chemicals that had been delivered and caused a release. We contacted the emergency services who assisted us."
Fraser said it was still uncertain why the incident happened but said the container the chemicals were housed in had been "neutralised" and posed no further danger. No other workers in the vicinity were affected.
Cleveland Fire Brigade also attended the scene, with Station Manager Ian Dixon saying: "We were called at 11:24am.
"Three appliances attended from Billingham, Thornaby and Stockton stations with four people taken to hospital with breathing difficulties after a chemical reaction.
"There was a process taking place with a small amount of chemical and we believe there was some reaction with a different chemical creating a very small gas cloud. It was a very small scale incident."
The Health and Safety Executive said it was aware of the incident and it would be "making initial inquiries and will be visiting the site to conduct an investigation".