WASHINGTON (Reuters) - A woman wearing sunglasses and dressed in black down to her white tennis shoes robbed two Washington banks within 15 minutes on Monday, threatening a teller by saying she had a gun, the Federal Bureau of Investigation said. The woman entered a PNC Bank in northwest Washington at 9:13 a.m. EST and passed a note to a teller demanding money. The robber got money and left the bank, the FBI said in a statement. The woman next turned up at a Bank of America Corp branch in northwest Washington at 9:28 a.m. EST, asked the teller for money and saying she had a gun. She again got the money and left, the FBI said. An FBI spokesman declined to give the amounts stolen.