INQUIRIES are being made after an explosion at a factory rocked nearby homes.
Families living near the Thomas Bolton works at Froghall reported hearing a blast which shook their houses and produced an orange cloud of smoke.
A spokesman for the Health and Safety Executive (HSE) has told the Post & Times it is now investigating the incident.
A spokesman said: "We are aware of the incident and were making enquiries."
Community leaders have called on the firm to "put residents' minds at rest" about safety at the site.
Froghall resident and Leek businessman Dave Felstead was watching television with his wife Pauline when they heard a loud bang.
Mr Felstead, who lives at Bank View, said: "We were in the lounge when we heard a huge explosion which shook our house and also our neighbour's property.
"It was so fierce it opened all the internal doors of our house.
"We went outside and looked over the Bolton site from the rear of our garden, where we saw a huge amount of smoke which was orange in colour.
"It was very heavy all over the factory area, and it looked just like a volcano had erupted.
"My neighbour said at the time it had blown a hole in one of the building's roof, which seemed to be in one of the older parts of the factory.
"After seeing what had happened I immediately rang the fire service."
Ward councillor for the area, Linda Malyon, said she had spoken to someone who was travelling past at the time, on Wednesday evening.
She said: "I have been told it was frightening and like a bonfire, with fireworks going through the roof and a lot of vibration.
"It was lucky no-one was hurt. I now want the factory management to make a public statement on what went on so it puts residents' minds at rest for the future."
Staffordshire Fire and Rescue Service said it received a call to the factory at 9.11pm and mobilised two appliances to the scene.
A spokesman said: "One crew from Ipstones and one from Cheadle attended an incident at a factory on Froghall Road in Froghall at 9.11pm on Wednesday evening.
"There was an 'explosion' in the production plant which also caused sheeting to blow of the roof.
"Firefighters used one hose reel jet to put the fire out before damping down and leaving the scene at 11.08pm. The incident has been classed as accidental."
The factory supplies copper products for the power industry.
One worker at the factory told the Post & Times that he believed a furnace had blown up.
He said: " It blew holes in the roof and smashed windows. Luckily no-one was hurt.
"There is a lot of damage and the premises have been sealed off."
A spokesman for Staffordshire Moorlands District Council said it would be sending an official to the site.
She added: "The council is not formally involved as it is HSE enforcement for health and safety and the Environment Agency for any issues around land contamination.
"However, the company does run an industrial process permitted by the council, so an officer will be visiting to see whether the incident impacts on this authorisation."
When contacted by the Post & Times a spokesman for Thomas Bolton, which employs around 100 people at Froghall, said it had no comment to make.