Philadelphia police are asking for the public's help in identifying three men in surveillance tapes made during a robbery Sunday night at the Hess gas station at 2400 Castor Ave. in Kensington.

At least seven robberies in the Kensington area have been reported since Saturday, according to Sgt. Donna Bachmayer of the East Detective Division.

Bachmayer said one man could be a witness who could help identify the two men who enter the shop shortly afterward. One of those men jumped the counter and put a knife to the cashier's head while the other robber pointed a gun at a second cashier.

The employees were ordered to empty the cash drawers, which they did, Bachmayer said.

Police believe four robberies on Saturday and three on Sunday could be related to the Hess hold-up. The four on Saturday began at at 12:01 a.m., when a man was robbed outside 3367 Coral St.; at 8:15 p.m. robbery at the Crispy Pizza at 1858 E. Allegheny Ave., an 10:30 p.m. robbery at Santucci's at 4019 O St., and a 11:15 p.m. robbery at the New Pizza at 2084 E. Allegheny Ave. The Sunday robberies occurred at the Hess station, and then at 6:46 p.m. at a grocery store at 3300 Mutter St. and again at 7:15 p.m. at a grocery store on 4353 Fifth St.

Police said one of the robbers is about 20 to 25 years old, about 5-9 and 145 pounds. He was wearing jeans, a long black down jacket, and a hooded sweatshirt with a skull or skeleton pictured on the front. He carried a black revolver.

The other was about 17 to 20, 5-6 to 5-8, with a slim build and weighing about 120 pounds. He was seen wearing a black bomber jacket with a fur collar and a black knit hat that he sometimes pulled over his face.

Another man is a witness or possibly a third robber, about 20 to 25 years old, 5-9, about 160 pounds, with a round two-inch tattoo on the right side of his neck.

Anyone with information about the robberies is asked to call East Detectives at 215-686-3243.

Contact staff writer Barbara Boyer at 215-854-2641 or bboyer@phillynews.com.