Authorities say the woman handed a note to a teller at a credit union in the Columbus area Thursday saying she had a gun and wanted a lot of cash.
Investigators say the same woman robbed two banks earlier in the week, both in the Columbus area.
FBI Special Agent Harry Trombitas says three bank robberies by the same person in a week is rare for anyone, male or female.
Trombitas says several investigators recall the same woman robbing a bank in Columbus in January 2006.
The FBI says only 6 percent of the more than 7,000 bank robberies reported nationally last year were committed by women.
Information from: The Columbus Dispatch, http://www.dispatch.com