There are fears chemicals could ignite at an aerospace firm's factory where a massive fire has erupted.
The blaze broke out at Nu-Pro's factory in Stroud shortly after 20:00 BST.
Nearby businesses have been evacuated and police have urged residents in the area to stay indoors and shut all doors and windows.
Police told BBC reporter Ellie Pitt, who is at the scene, that chemicals are used at the site. The Environment Agency is assisting firefighters.
Nu-Pro, based at the Eagle Works site in Thrupp, manufactures parts used in the aerospace and defence industries.
Its website says the unit is in "an industrial heritage conservation area with the River Frome running through its grounds" and it has "considerable obligations to the environment".
The fire in Stroud Police told BBC reporter, Ellie Pitt, there were chemicals at the site of the fire
The industrial building is around 50m (164ft) by 30m (98ft) in size, is well alight and fire crews are expected to be there for some time.
A spokesperson for Gloucestershire Fire and Rescue Service added: "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."
Read more: http://www.bbc.co.uk/news/uk-england-gloucestershire-28239930
Video report at link.