Faulty equipment is being investigated as the possible cause of a significant fire at a nuclear submarine shipyard in Cumbria, Sky News understands.
Videos and pictures posted on social media show flames and smoke billowing from BAE Systems in Barrow-in-Furness.
Two people were taken to hospital but Cumbria Police said there were no casualties after the fire broke out at around 12.30am on Wednesday.
The force said the response to the fire is ongoing and that people were evacuated from Devonshire Dock Hall.
It added there was no nuclear risk but Cumbria Police also had advised people living nearby to “remain indoors” and to “keep doors and windows closed”.
Donna Butler, 36, who lives beside the shipyard described the scene: “My son came and got me and said that the BAE alarms were going off.”
“When I opened the front door, we just saw a lot of black smoke… really thick black smoke, and it was very loud,” she told the PA news agency.
Another resident Jeff Holt, 43, said he could smell burning, adding that the fire “looked pretty serious”, while a taxi driver described how the blaze had caused traffic tailbacks.
BAE Systems is one of the world’s biggest defence contractors.
It produces a huge array of military hardware and technology – including nuclear submarines, fighter jets, tanks and ships, as well as guns and ammunition.
It also builds type 26 frigates for the Royal Navy and makes electronic warfare systems for F-35 fighter jets.
The company’s site in Barrow-in-Furness is where it constructs Astute and Dreadnought nuclear submarines for the Navy.
BAE Systems has built all but three of the Royal Navy’s nuclear submarines since 1963.
Sky News understands that the fire is not being linked to any ‘foreign entities’.
In a statement, the Ministry of Defence released few extra details but said: “We are working closely with the emergency services and BAE Systems… and wish those who have required hospital treatment a quick recovery.”
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In April, an investigation was launched after an explosion at a different factory owned by BAE Systems.
No one was injured in the blast in Glascoed, Monmouthshire, South Wales.