Philadelphia police are actively investigating a series of armed robberies in Center City, specifically focusing on incidents involving suspects armed with firearms that appeared to be AR-15-style rifles. The most recent incident occurred around 2:15 a.m. on Friday on the 1500 block of Sansom Street. According to law enforcement, a 23-year-old man and two friends were returning home when they were confronted by two masked men who exited a light gray or beige four-door sedan with tinted windows. The suspects demanded the victim's silver diamond watch and stole two gold chains from his neck. One of the robbers was armed with an AR-15-style rifle, while the second carried a black handgun. The suspects fled west on Sansom Street, and no injuries were reported in this specific encounter. This event is believed to be connected to a similar robbery that took place less than a week prior, around 3 a.m. on Sunday, on the 1500 block of Locust Street. In that earlier incident, three individuals were robbed at gunpoint by masked men carrying handguns and an AR-15-style rifle. The suspects in the Locust Street robbery stole cellphones, watches, car keys, wallets, driver's licenses, and cash before fleeing in a Honda. Authorities have not yet made any arrests in either case and are seeking the public's assistance. Investigators are looking for at least four individuals in total across the connected cases. The Philadelphia Police Department urges anyone with information regarding these crimes to contact them by calling 215-686-TIPS (8477). The investigation remains ongoing as police work to identify and apprehend the suspects responsible for these violent crimes.