Fire crews are fighting a blaze at a tyre recycling firm in Grimethorpe.
The fire, involving a large number of tyres, is on the Springvale Road industrial estate, and was spotted at 5am this morning.
Nearby residents have been warned to keep doors and windows closed to keep out smoke and fumes, and some people arriving for work in the area have had to be turned back.
Four fire engines with an Aeriel Ladder Platform and a Command Support Unit attended initially but have been joined by further appliances, and specialised foam suitable for this type of incident is to be used.
A South Yorkshire fire service spokeswoman said: “A large amount of tyres were well alight when crews arrived. Firefighters wearing breathing apparatus are using main jets to tackle the blaze and have worked hard to prevent the fire from spreading to nearby premises.
“Fire crews are advising members of the public to keep their doors and windows closed as there is a large amount of smoke in the area.”
The operation is expected to continue for most of the day.
An investigation into the cause of the fire will begin once the fire is out.