MINNEAPOLIS (WCCO) — One Xcel Energy employee was injured and 50 were evacuated after a fire at the Black Dog Generating Station in Burnsville Monday morning, according to Xcel Energy.

The flames were reported at 7:30 a.m. coming from the plant’s Unit 4 coal bunker, and nearly 60 firefighters worked for hours to contain them in the four-story structure.

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One power plant employee was hospitalized. Their condition is not known.

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The evacuated employees later returned to the plant, which is still operational.

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The cause of the fire is under investigation.