Residents living next to a nuclear submarine shipyard saw thick smoke and bright flashes as a fire broke out in the early hours of the morning.
Two people were taken to hospital for smoke inhalation after emergency services were called to the fire at the BAE Systems shipyard in Barrow-in-Furness, Cumbria, at about 12.45am on Wednesday, police said.
BAE said the pair were workers at the site and they have since been released from hospital.
Cumbria Constabulary said there was no nuclear risk and, in an update shortly before 3pm, said firefighters had suppressed the blaze and moved to dampening down.
A multi-agency investigation is ongoing to establish the cause of the fire, the force said.
Debbie Holliday, 37, who lives opposite the Devonshire Dock Hall where the fire started, said she was woken by the alarm from the site and could see “lots of smoke”.
She told the PA news agency: “It was quite thick and you could see the fire on the top of the building. I started to get more concerned when I saw flames on the roof.
“We just stayed inside and shut the windows.”
“The children slept through it but I have the front bedroom. I could hear what sounded like fireworks as well as the alarm and could see bright flashes where the fire was.
“It lasted 45 minutes, or maybe more.”
Videos shared on social media show flames shooting out from the building, with alarms blaring.
Later on Wednesday morning, the smoke had cleared but areas around the roof of the dock hall appeared slightly blackened and fire vehicles were seen going to and from the site.
Donna Butler, 36, told PA: “My son came and got me and said that the BAE alarms were going off, so we went.
“It was a lot of black smoke, like really thick black smoke, and it was very loud.”
She said a few police cars and emergency service vehicles were at the shipyard and police were asking people to stay in their homes.
Another resident, Jeff Holt, 43, said the fire “looked pretty serious” and he could smell burning.
The care worker told PA: “My house is maybe a mile as the crow flies and as soon as I stepped outside I could smell the burning and smoke, that’s how intense it must have been at that time.”
Other neighbours said they slept through the dramatic scenes and learnt of the fire when they woke to phone calls from concerned friends and family members, or saw videos of it online and on the news.
One worker said he had been sent home from the site after turning up for his shift at 6am.
Michaelson Bridge was closed following the fire but it was reopened to traffic later in the morning.
In the afternoon, police said they were no longer advising residents of the need to keep doors and windows closed.
The facility is home to Britain’s Astute-class submarines and Dreadnought programme.
A BAE Systems spokesman said: “The area around the Devonshire Dock Hall has been evacuated and everyone has been accounted for.
“Two colleagues were taken to hospital having suffered suspected smoke inhalation and have both since been released.”
Shares in the FTSE 100-listed company fell as much as 2% in morning trading on Wednesday.