The man demanded money from the credit-union employees and fled the scene once he got it.
FBI investigators said a second suspect helped the armed man get away.
The suspect who went into the credit union is described as a man of unknown race between 20 and 35 years old. He's between 5 feet 8 inches and 6 feet tall with a medium build. He was wearing a dark hooded sweatshirt, dark gloves and blue jeans. He also had a dark mask covering his face.
The weapon he had was a black semi-automatic handgun.
Investigators did not have a description of the second suspect.
DSFCU is offering a $5,000 reward for information leading to the arrest and conviction of the suspects. If you have any information regarding this incident, please contact the FBI at 602-279-5511 or Silent Witness at 480-WITNESS (948-6377), 1-800-343-TIPS (8477) or 480-TESTIGO (837-8446).