Police are investigating six bank robberies that have taken place in just seven weeks in the city of Norwalk.

The most recent incident was at the Bank of America on Wall Street, which was robbed Thursday. Police say the suspect passed a note to the teller demanding cash then lifted his shirt revealing what appeared to be the butt of a gun. The man got away with about $2,000.

According to police, the Bank of America on Main Avenue was hit on May 3, Wachovia Bank on Connecticut Avenue on May 16, the Bank of America branch on Winfield Street May 23, Citibank on Main Avenue and Patriot Bank on Westport Avenue on June 4.

The Norwalk Police Department is investigating along with the FBI Bank Robbery Unit, Fairfield County Detective Association and state police.