The fire at a South Side industrial complex in Columbus, Ohio

Overheated forklift brakes have been identified as the probable cause of a factory fire in a sprawling South Side industrial complex in Columbus, Ohio.

The Columbus Dispatch quotes assistant fire chief Karry Ellis as saying employees were trying to repair the brakes when a fire sparked and "got tangled up in some cardboard".

However, he stresses that investigators continue to examine several things in the area of the fire's origin and that final determination will take time.

The extensive fire is expected to smoulder for several days and the damage bill could run to USD8 million.

The fire, at the site which houses Universal Paper & Plastics Inc., Columbus Pallet Recycling and ABECO Materials, spread quickly because of the quantity of flammable material, according to reports.

Phoenix Recycling, United Paper & Plastics and United Plastics also are associated with the address.

Aerial photos of the property before the blaze show stacks of cardboard and wood across much of what is listed as almost 13 ac. (52,610 sqm). Witnesses say some of the tightly packed pallet stacks were 30 ft. (9 m) high.

While no-one was hurt in the blaze, officials were initially concerned about toxins from plastics burning at the site, but air-quality test results showed nothing untoward, according to the Environmental Protection Agency.

Footage of the fire can be seen here.