The TCF Bank branch in the Westmont Jewel at Cass and Ogden avenues was robbed just before 9 a.m. Friday, police said.
The FBI does not have anyone in custody.
The robber did not show a weapon, according to BanditTrackerChicago.com.
The man is described as between 20 and 30, around 5'11" to 6'1," wearing a construction hat and vest, tan shirt and dark pants, according to Bandit Tracker Chicago.
Westmont police could not provide details on the incident.
"Since TCF is federally insured, the FBI is handling the investigation," said Sgt. Steve Thompson, Westmont Police Department.