To help find the culprits, police are offering a $50,000 reward for anyone with information leading to a conviction.
Authorities were called out to the report of a robbery at around 2:15 p.m. at the U.S. Post Office at 8227 Germantown Avenue.
Police say two males wearing hoods and masks and armed with guns entered the post office, jumped the counter, and demanded money.
"All of a sudden I heard screaming, looked up, I thought, 'my goodness, the girl [clerk] must have a mouse or something back there,'" a witness told Action News. "He kept asking her to open the drawer and then he disappeared."
The robbers took off with around $600.
Police believe the two men fled away in a white car.
The United States Postal Inspection Service and Philadelphia police are working on the investigation, brushing for fingerprints at the store, talking to witnesses and gathering evidence. Robbing a post office is a federal offense. Authorities say finding these men is a top priority.
"They're looking for money, they're looking for stamps; I can't tell you exactly what they're looking for, but it's stupid. There's nothing worth spending time in federal prison," U.S. Postal Inspector Reginald Wade said.
The first suspect is described as a black male, between 6'3 to 6'5 tall, with a medium to dark complexion, thin, but athletic build with a goatee. He was wearing a dark blue hooded sweatshirt, dark grey pants, and a navy blue turtleneck covering his mouth. He is said to have a deep baritone voice .
The second suspect is described as a black male, 5'8 to 5'10 tall, with a medium to dark complexion, bald, and a stocky build. He was wearing a sleeveless puffy blue vest and a similar navy colored turtle neck covering his mouth.
Authorities do have surveillance footage and will release an image of the suspects.
Anyone with information is asked to contact the Philadelphia Division of the US Postal Inspection Service at 1-877-876-2455 (US-MAIL-5) or on their website at www.postalinspectors.uspis.gov