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.

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.

The woman was transported to Northwestern Hospital.

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