FIRE crews are currently tackling a major blaze at Eagle Works, near Stroud.
Eight appliances and an aerial appliance have attended the incident in London Road, Thrupp and explosions can be heard as the fire grows.
It is believed that the Nu-Pro aerospace factory site is seriously affected by the fire which showed no sign of abating as darkness fell.
Police at the scene said chemicals were used at the site, and the Environment Agency is assisting the fire and rescue service.
Thick black smoke can be seen across the town and a massive pall is heading out across the Golden Valley, over Minchinhampton and towards Cirencester.
People are being told to stay indoors and shut doors and windows. The fire started at around 8pm.
An industrial building is 'well alight' say Gloucestershire Fire and Rescue Service which continues to tackle the major incident at the site.
The 50m by 30m industrial building was 'well alight' said a spokesman for the fire service at 9pm.
"We expect to attend for some time," she said, adding that they were unable to say whether there were any casualties.
Initially five fire appliances attended and a further three are now also at the scene, as well as an aerial appliance. Firefighters have been using three water jets, and four sets of breathing apparatus have been used.
"Black smoke was suddenly pouring up the valley. It was coming up from the road and really smelt horrible," said Coryn Memory, who lives in Thrupp.
"People who were down there on London Road had cloths over their mouths."
Nearby residents on the London Road turned back drivers until the emergency services reached the scene, resulting in gridlock on the narrow Thrupp Lane.
Nearby Bagpath Lane was clogged with cars, many parked by onlookers trying to get a better look at the blaze.
Resident Ben Miller was feeding his sheep near the site when he heard explosions and saw flames coming from a brick-built building.
The blaze rapidly engulfed the building and despite the efforts of a major fire and rescue service presence, it appeared to worsen. Each explosion heralded more plumes of smoke which reached several hundred feet in the air and at least a mile long.
Stroud Life and Citizen reporters on the scene could see fierce flames engulfing the roof of the more modern building. Its metal roof buckled and melted in the intense heat.
A police spokesman said: "A serious fire has broken out at the Eagle Works, London Road, Stroud, and local residents are being urged to stay indoors, shut doors and windows and closely monitor news updates.
"Emergency services were called to the scene at about 8.20pm following reports of thick black smoke coming from the factory and covering the A419.
"The A419 has now been closed at the junction with London Road.
"The Fire Service is currently on site to deal with the fire, which may take some time to extinguish. It is not known at this time what caused the fire."
Motorists and residents are being urged to:
-Avoid the area if possible, and keep off the A419/London Road
-Stay indoors
-Shut all doors and windows
-Monitor any news updates about the situation.
A Spokesperson for Gloucestershire Fire and Rescue Service, issued a further statement just before midnight "Gloucestershire firefighters are dealing with a large fire at Griffin Mill, London Road in Thrupp, Stroud.
"Crews arrived at the scene just before 8.30pm this evening. There are currently fifteen fire engines and one aerial vehicle on site.
"Around 60 firefighters are tackling the fire using eight jets and 12 breathing apparatus. The industrial building around 50x30 metres is well alight and firefighters are expected to be there for some time. Due to chemicals that are thought to be contained in the building neighbouring units have been evacuated and local residents are being encouraged to stay indoors and keep their windows closed."
