Fire in optical machinery
The alert was received at around 9.10pm and two fire crews from Ross-on-Wye fire station attended.
Station Commander Martin Lown from HWFRS said: "The fire had broken out in machinery used for the manufacture of glass lenses and is believed to have been caused by a vapour explosion inside one of the machines."
He explained that the unit operates 24 hours a day and that a member of staff had tackled the fire using a CO2 (carbon dioxide) extinguisher after hearing the explosion in the grinding machine.
Firefighters in breathing apparatus then went into the unit and used a hose reel to ensure the fire was fully extinguished and to ventilate the premises.
While there were no injuries as a result of the incident, the grinder involved in the fire was destroyed and there was also some heat damage in the factory unit near the machine.
Firefighters have since called at other commercial premises in the area to offer relevant fire safety advice.