Thirty-seven people have been injured in a toxic leak at a chemical factory on Teesside.
All the casualties suffered burns, skin irritation and breathing difficulties at the BASF site in Seal Sands, near Billingham, on Thursday morning.
According to the North East Ambulance Service, 17 people have been taken to hospital, one with serious burns.
The 20 remaining casualties were decontaminated and discharged. BASF is investigating the cause of the leak.
Nine people have been taken to the James Cook Hospital in Middlesbrough, and seven to North Tees Hospital.
The man suffering from serious burns is being treated at Newcastle's Royal Victoria Infirmary.
The chemical involved is hexamethylenediamine, used in the manufacture of a wide range of plastics.
It is corrosive and can be hazardous in high concentrations.
A BASF spokesman said 14 employees were taken to hospital as a "precautionary measure".
"A further three BASF employees have been taken to hospital and require further treatment," he said.
"The cause of the event has not yet been identified and an investigation into this incident will be initiated as soon as possible and will involve the Health and Safety Executive and the Environment Agency."
Ambulance and fire crews from across the region responded to the leak, which happened at around 0930 GMT at the company's Nylon Intermediates plant.