(CBS) — A 25-year-old woman fell to her death on Lower Wacker Drive in the Lakeshore East area early Sunday morning.

CBS 2’s Jeremy Ross reports police are describing it as a terrible accident.

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The woman was leaning over the railing on Upper Wacker and fell to Lower Wacker, police said. She was pronounced dead on the scene.

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The woman has been identified as Generra Lee, a mother of three children. A friend of Lee’s said she was on a party bus prior to the fall.

A man familiar with the area believes about four stories separate Upper Wacker from the ground below.

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Police are calling it a death investigation.