It took about an hour for firefighters to bring the July 4 blaze under control.

Portland fire officials are still trying to determine what caused the July Fourth fire that destroyed towers of pallets in Northeast Portland, the city said.

The three-alarm fire caused significant damage to Mr. Pallets, the pallet-recycling business near Whitaker Pond, on Northeast 47th Street, but resulted in no injuries. Flames reached up to 30 feet high.

Trailers parked at a business immediately east of Mr. Pallets, Maxim Crane Works, also sustained damage, likely causing “a very significant loss,” Portland Fire & Rescue spokesperson Lt. Damon Simmons said in an email Monday.

The main building on the property was badly damaged, Portland Fire & Rescue said.

Mr. Pallets is registered to Mario Ruiz. The Oregon Department of Environmental Quality fined the company $16,928 in November, alleging the company was “conducting industrial activity” that could lead to polluted stormwater discharge without applying for a permit to do so. Ruiz couldn’t immediately be reached for comment.

— Fedor Zarkhin is a breaking news and enterprise reporter with a focus on crime. Reach him at 971-373-2905; fzarkhin@oregonian.

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