BOSTON -- Boston police are investigating a report of a sexual assault in the city's North End neighborhood on Wednesday.

At about 3:15 a.m. Wednesday, a woman told police that she was sexually assaulted on Richmond Street near Fulton Street. The woman said she was grabbed from behind and sexually assaulted. She said there was a brief struggle before her assailant fled.

The assailant is described as a white male in his late 20s, approximately 5 foot 8 inches to 5 foot 10 inches tall with dirty blond hair and a thin-to-medium build. He was wearing a navy blue or black baseball hat with an unknown logo, a white ribbed tank top, dark colored shorts that came down to his knees and dark-colored shoes.

Anyone with information is asked to contact Boston police at 1-800-494-TIPS or text the word 'TIP' to CRIME (27463).