Eight fire engines from across Greater Manchester and Lancashire, as well as an aerial appliance, were working to bring the blaze under control at Kirkless Industrial Estate, on Cale Lane, New Springs, on Saturday morning.
They were called at 5.45am to a fire involving around 400 vehicles, understood to be located in a scrapyard.
One witness reported that a second unit on the industrial estate had also been affected by the fire.
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Residents reported hearing several loud explosions throughout the morning and feeling their houses shake, with people as far away as Beech Hill and Blackrod being affected.
On Wigan Today's Facebook page, Stewart Fletcher said: "A massive explosion at 8.20am shook the house and I live a mile away."
Alison Every said: "I heard from Durham Street in Whelley it was loud!!"
Kerry Tomlinson said: "Shook our house in Whelley near spar bad that hope everyone is ok who lives near it."
People living nearby were urged to keep their doors and windows closed and people were asked to avoid the area as firefighters continued to work.
A spokesman for Greater Manchester Fire and Rescue Service said: "At 5.45am on November 14 our crews were called to reports of a fire at Kirkless Industrial Estate.
"Firefighters from Wigan, Salford, Bolton, Stockport and Rochdale were quickly on the scene of the fire and are using jets, spray plates as well as specialist appliances - the Stinger and the Scorpion - to fight the fire involving a large quantity of vehicles. Firefighters remain on the scene of the incident.
"Residents are being asked to keep their windows and doors closed at this time due to the large quantity of smoke issuing from the fire."
The incident was being scaled back by the fire service by 9.15am, but several crews remained on the industrial estate throughout Saturday to ensure the blaze was fully extinguished.
The fire service said it was working with other organisations to reduce the environmental impact of the blaze.
Station manager Andy Hardman said: “Our crews continue to work extremely hard to extinguish this fire. They have made excellent progress this morning and have now scaled back the incident significantly.
"We would like to thank residents for their co-operation so far and to please continue to keep their windows and doors closed.
"I'd like to praise the hard work of all of the crews who have been fighting this fire this morning.”
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