Around 100 firefighters are tackling a "severe" fire at a paper mill.
More than 15 fire engines and their crews are tackling the blaze at the Smurfit Kappa plant in the Nechells area of Birmingham, West Midlands Fire Service said.
The site in Mount Street is a recycled packaging mill, according to the company website.
A fire service spokesman said the fire was in "a very large outside storage area, containing cardboard bales". He said: "Approx 100 fire fighters are on scene along with multi-agency partners who are working to contain the blaze and to stop further fire spread."
According to its website Smurfit Kappa is one of the leading producers of paper-based packaging in the world with more than 41,000 employees in 32 countries.
West Midlands Police said high winds were hampering efforts to extinguish the fire, which started just after 10pm on Wednesday night.
It said a police helicopter was being used to see if the fire had spread to other parts of the industrial estate the paper mill is on.
"Motorway officers are also monitoring fire due to proximity to M6. No traffic problems at this stage," the force tweeted.
The fire service later said 10,000 tonnes of recycled cardboard bales was on fire in an area of around seven acres. A spokesman tweeted: "Fire is contain to storage area, high winds are hampering fire fighting, however crews and other agencies are working extremely hard to bring blaze under control."
Local residents were urged to stay indoors with windows and doors shut, although a spokesman said that the material burning is only thought to be cardboard and non-toxic.