CHICAGO (CBS) -- Chicago Police are searching for a man who sexually assaulted a woman after he asked her for directions. 

Around 11:30 Friday night, a man on a silver bike with green lettering or stripes went up to a 20-year-old woman in the 1500 block of West Thomas Street in Noble Square. 

When the woman started giving directions, the man pulled out a gun and sexually assaulted the victim. 

Police say the man wore a gray sweatshirt and a blue face mask covering his chin. He is described as a hispanic man between 18 and 25. 

Anyone with information is asked to call Area Three detectives at (312)744-8261. Anonymous tips can also be submitted at cpdtip.com.