Authorities are investigating the death of a woman at a wastewater treatment facility Monday in Baltimore.

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The woman was a longtime employee at the Patapsco Wastewater Treatment Plant in Wagner's Point, WJZ-TV reported, as well as a plant supervisor and former employee of the month.

Another worker reported the unnamed victim missing after noticing that she walked across a catwalk above a water filtration system, then seemed to disappear, according to The Baltimore Sun.

Plant spokeswoman Blair Adams told the Sun that the woman's body was located inside a large vat of water.

It's unclear what happened or how the worker ended up in the filtration system, but WMAR-TV reported she would have fallen 20 feet when she entered the water.

An investigation is underway.