SACRAMENTO (CBS13) – Winds that made sagging power lines come into contact has been found to be the cause of the deadly 2017 Cascade Fire in Yuba County.

The Cascade Fire started in October 2017 and went onto burn 9,989 acres. More than 250 structures were destroyed and four civilians died, officials say. A firefighter was also injured.

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Tuesday, just over a year to the date the fire started, Cal Fire announced their findings on what caused the fire. Investigators say a high wind event going on in the area caused two sagging power lines to come into contact – creating an electrical arc.

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Molten material fell to the ground, onto a bed of receptive fuel, and the fire started.

The power line was owned by PG&E, Cal Fire says.

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Cal Fire is continuing to investigate the other fires that started in October of that year.