Firefighters worked throughout the night to tackle a large blaze at a mill which was once home to one of Wigan's oldest companies.
Smoke could be seen billowing from the former Potter's Herbals factory in Marylebone on Thursday evening and crews rushed to tackle the fire.
But despite their best efforts, with firefighters working at the site on Leyland Mill Lane during the night and into Friday, the building could not be saved.
Gareth Gray, watch manager at Wigan fire station, said: "There's a lot of damage to the building. We have an inspector going to check on the building this morning and I think it will be condemned and knocked down. It's unsafe to enter."
The derelict mill was already well alight when four fire engines, along with an aerial appliance, were called to the mill at 7.30pm.
Mr Gray said: "The whole of the building was on fire. As soon as we turned out of the station, we could see large quantities of black smoke. When we got there, the building was well alight.
"We had to cut our way in through a big iron gate put there to secure the site. It's all overgrown so we had to make our way through the trees."
Firefighters could see the brickwork collapsing as the flames engulfed the building and realised it was too dangerous to go inside.
Instead, they cordoned off the site and fought the fire from outside the mill, using water from the nearby River Douglas to tackle the flames.
While it was clear the mill was badly damaged, they worked to make sure the fire did not spread to neighbouring properties.
Crews fought the fire until 12.30am and continued damping down throughout the night. They expect to be on the site all day on Friday as work continues.
The fire is believed to have been started deliberately and police have been informed.
Mr Gray urged people to stay away from the site as it is now extremely unsafe.
He said: "If people know the area, make sure their kids stay away because the site is dangerous. There are holes in the floor and shafts they could fall down because it is not lit up."
Becca Heron, director of economy and skills at Wigan Council said: “We are aware of a fire overnight at an unlisted mill on Leyland Mill Lane.
"The building control team is currently on site with the fire service and we will work together to ensure the area is secured.
"We would like to reassure the public that we will keep them informed with any updates.”
Anyone with information about the fire is asked to call police on 101.