A masked man with a gun allegedly sexually assaulted a woman early Thursday morning in Jamaica Plain, Boston police said.

Police responded to the area of Gay Head and Minden streets around 1:41 a.m. The incident occurred when the woman was on Gay Head Street and the suspect allegedly approached her with a gun, demanded her cellphone and then told her to walk with him to a backyard where she says he sexually assaulted her, according to police.

The suspect was lat seen running down Arklow Street toward Walden Street.

The victim described the suspect to police as having a mask pulled up over his nose and wearing a black hooded sweatshirt with a white logo on the front and black jeans. 

This incident is the   second reported sexual assault in the neighborhood within the past week. Last Thursday, a woman was walking around Jamaica Pond at night when an unknown man approached her and assaulted her, police said. 

Police are asking anyone with information to call 617343-4400 and advise anyone who has been a victim of sexual assault to call the Boston Area Rape Crisis Center (BARCC) at 1-800-841-8371.