The FBI said the suspects have been involved in at least six robberies at BMO Harris banks in the south and west suburbs since June.
Those with more information can earn up to a $20,000 if that information leads to an arrest.
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The BMO Harris in Woodridge was the latest target. Two "bundled bandits" went to the front door at 9:53 a.m. on Friday. Investigators believe the suspects shattered the locked door, but they fled and did not enter the bank.
The FBI described one suspect as being over 6-feet tall with a slim build, approximately 160 pounds. He or she was wearing a black hoodie with the hood up, a black mask, dark pants and was armed with a semi-automatic handgun.
FBI described the other suspect as wearing a dark hoodie, a green reflective construction vest and a mask.
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Tips can be reported, even anonymously, to tips.fbi.gov or by calling 1-800-CALL-FBI.
Bank robbery attempt locations and times:
BMO Matteson on June 10, 2023
BMO Frankfort on June 17, 2023
BMO Bolingbrook on July 1, 2023
BMO Naperville on July 19, 2023
BMO Addison on July 21, 2023
BMO Woodridge July 28, 2023