(KRON) -- Authorities in Palo Alto are investigating a reported sexual assault that occurred last week near the city’s downtown transit center, the Palo Alto Police Department announced Friday. The victim, a woman in her 30s, reported the sexual assault to police on Wednesday. Investigators learned that the woman was waiting for a bus at the Palo Alto Transit Center on Nov. 4  when an unknown man approached her. The man, police said, asked the victim if she would help translate a conversation with another man nearby. After agreeing, the victim followed the man to a nearby tree line. No other person was waiting there. The man gestured toward a knife clipped to his pants pocket and threatened to harm the victim before sexually assaulting her, according to police. The suspect then fled on foot in an unknown direction. Morgan Hill man killed in three-vehicle crash Due to the threats made by the suspect, the woman did not initially report the incident to authorities, Palo Alto PD said. The woman described the suspect as a slender Black man in his 30s wearing a black hooded sweatshirt, black cargo pants and a surgical-type mask. Palo Alto police said there have been no other similar incidents within the city recently. Anyone with information is asked to contact the Palo Alto Police Department at (650)-329-2413. Anonymous tips can be emailed to [email protected] or texted to (650)-383-8984.