More than 100 firefighters tackling a huge blaze on an industrial estate in Leeds saved nearby buildings from “certain destruction”.
Crews battled the fire at chemical recycling firm Tradpak in Armley, which sent thick smoke over the city.
A fire service spokesman said “a significant number” of properties had been saved.
West Yorkshire Police said it was now investigating the cause of the blaze, which erupted just before 02:00 BST.
Armley fire Firefighters saved a number of nearby buildings from ‘certain destruction’ in the blaze at Tradpak, Armley
Nearby roads were closed and buildings, including a nightclub, were evacuated.
West Yorkshire Fire and Rescue said there was a large amount of chemicals and cylinders at the Albion Way site.
People in the city centre were warned to keep windows and doors closed due to potentially hazardous chemicals on the site.
Armley fire West Yorkshire Police is now investigating the cause of the blaze
Supt Mabs Hussain of Leeds District Police, said: “I want to reassure residents that everything has been done to get the fire under control, and minimise the effect on residents.
“We can also confirm that the smoke from the fire is not toxic. However, as a precaution, we have continued to advise people near the site to keep doors and windows shut.”
Anja Swan, a student at Leeds Metropolitan University, said she heard explosions that sounded like thunder.
“We could see massive, massive clouds of thick black smoke, just billowing out into the air,” she said
“There were fireballs shooting. It was really ferocious. Like Armageddon.”
Armley fire Fire crews have been scaled back but are expected to stay at the scene throughout the day
Louise Fryer, who could hear the explosions two miles away in Wortley where she lives, said: “It’s scary, isn’t it, how quickly something like that can spread.
“It’s under control but it’s still not out.”
The fire service urged people not come to watch crews dealing with the fire, which has been “surrounded”.
A spokesman said: “The fire involved two buildings and crews worked hard to prevent further spread to surrounding property.
“Significant numbers of adjacent properties were saved from certain destruction due to the hard work and dedication of the firefighters on duty.”
Twitter users said they had been in the nearby Canal Mills nightclub when it was evacuated because of the fire.
Pat Hickey wrote: “Got evacuated from Canal Mills. Leeds is on fire.”
Eyewitness Gemma Rathbone: “We could see massive clouds of thick black smoke”
Gemma Rathbone, who lives about half a mile from the site of the fire, said she was woken up by loud bangs at about 02:30 BST.
She and her housemate drove to the estate and said the roads were already blocked off by police.
“There were lots of people who had just come out of the club,” she said.
“It was just huge, absolutely massive, there was lots and lots of black smoke and there were still explosions. You could see when the fire got to a new bit of the building because there would be more explosions, it would go bang.”