Worcester police are investigating a series of armed robberies targeting pizza delivery drivers, with the fourth incident occurring early Thursday on Lund Street. The latest robbery involved two males, one armed with a gun, who demanded cash from the delivery driver, who was not injured. This follows three previous robberies in August, all involving similar circumstances and locations, with suspects approaching drivers under the pretense of food delivery. The first incident took place on August 12, followed by robberies on August 15 and August 18, all involving armed confrontations and theft of cash or valuables. Authorities are urging anyone with information to contact them, as the investigation into these crimes continues. Local pizza shop owners are reportedly increasing vigilance for late-night deliveries in response to these incidents.