CHICAGO (CBS) — Chicago police said a woman was sexually assaulted in the 100 block of East Randolph Street, not far from Millennium Park, around 4 Tuesday morning.

A 27-year-old woman was waiting on the Red Line platform at the State/Lake station when a male took her phone and started running.

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She chased after him into the street to the 100 block of East Randolph, where he sexually assaulted her and fled the scene, according to police.

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The woman was transported to Northwestern Hospital.

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CPD said no one is in custody. Area Central detectives are investigating.