CHICAGO (CBS) — Firefighters spent six hours battling huge flames raging overnight at a mulch business in Lockport.

The blaze at Homer Tree Service, at 16464 W. 143rd St. in Lockport, was so large, police shut down the nearby exit ramp on the Veterans Memorial Tollway.

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The fire started around 6 p.m., and the 20 to 25 employees at the mulch yard tried to keep it under control, but powerful winds caused the flames to quickly spread.

At least three area fire departments responded to the scene.

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At the peak of the blaze, flames were so intense, officials shut down the Archer Avenue exit ramp on the Veterans Memorial Tollway. Archer Avenue also was closed between 135th and 143rd streets while the fire was burning, but all have since reopened.

No injuries were reported.

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The cause of the fire was under investigation.