Daventry acid spill: Police officers and workers attend hospital
Workers spent four hours trapped inside their workplace because of an acid cloud outside.
One thousand litres of hydrochloric acid spilled into Hackwood Road in Daventry, Northamptonshire, earlier.
The spill happened while the acid was being delivered to the Metokote plant. Paul Kearns, from the firm, said staff had been medically checked out.
Two police officers who breathed in gases from the cloud have been sent home from hospital.
Warren Ellison, of Northants Fire and Rescue, said workers at the firm, which specialises in coating materials, were gathered together inside the building before they were escorted out.
"When they walked around the corner and saw the scale of the operation I think they were a bit surprised," Mr Ellison said.
Sgt Sam Dobbs, of Northamptonshire Police, said the affected officers had encountered a "very large cloud enveloping the whole building".
Roads in the area closed during the incident have now reopened.