CHICAGO (CBS) — A 70-year-old woman was brutally attacked early Thursday while out for her morning walk on a popular bike path in north suburban Zion.

The woman was walking on the Robert McClory Bike Path, near 31st Street and Galilee Avenue, around 6 a.m. Thursday, when she spotted a man on a bike watching her from a nearby bridge, police said.

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She turned around to go home, but the man caught up to her, and punched her once in the back of the head and twice in the face, knocking out several teeth. Police said she blacked out as a result of the attack.

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The victim described her attacker as a man dressed in all black, wearing sunglasses, and riding a bicycle.

Police said the motive for the attack is unknown. The woman was not sexually assaulted, and was not carrying anything of value.

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Anyone with information on the attack should call Zion police at 847-872-8000.