PHILADELPHIA -- Police believe the man responsible for sexually assaulting four women in Philadelphia last week struck again early Sunday morning.

Investigators with the Special Victims Unit said a man fitting the description of last week’s attacker robbed a 31-year-old woman at gunpoint, and then sexually assaulted her Sunday around 3 a.m.

Watch Video

The victim’s description of her attacker fits the description given by four other women robbed and assaulted last week -- including two on Thanksgiving morning. The attacker reportedly robs the women at gunpoint and then forces his hand down their pants.

The latest incident occurred on the 1800 block of Pine Street and police were still searching for the attacker Monday.

Last Wednesday, a 55-year-old woman was attacked at 17th and Folsom streets, and days earlier a 21-year-old was groped on South Street.

On Thanksgiving, police said, the man struck twice in the early-morning hours, first at 24th and Walnut streets and then at 25th and Spruce streets near a popular dog park.

Investigators said the attacker might have hidden by the Schuylkill River in between those two attacks.

“I can't tell you what's in his mind but there's always the chance he can go farther, and someone can get hurt,” an investigator said.

Police don't have a good description of the perpetrator and they urged women to be extra careful until the man is taken off of the street.

They want women to be aware of their surroundings, look around, travel in numbers and go with their gut instincts.