A Blue Island city official said the attempted robbery took place in the parking lot of a U.S. Bank located at 11960 S. Western Ave.
It involved a group of people just after 10 a.m., city officials said.
No one is in custody, the official said.
No bank employees were injured.
Chopper 7 was over the scene about 10:30 a.m. There was police tape surrounding the bank.
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There were also evidence markers on the ground in the parking lot and street. A large gun was visible on the sidewalk and a door on the bank appeared to be shattered.
Someone who lives nearby said they heard about six gunshots in the area.
An employee at the Old National Bank across the street said they are on lockdown.
Police appeared to be blocking part of the roadway in front of the bank, as well.
A spokesperson for the bank said no employees were involved.
But a US Bank customer was inside the bank at the time of the attempted robbery.
He said he was waiting in line to talk to a teller when shots rang out.
"I just heard the shots. I don't know which way, till I heard the glass broken," Juan said. "I didn't know what was going on until somebody said, 'get on the floor.'"
He said he immediately hit the deck until it was safe to get up.
A woman who works across the street didn't want to be identified but says the gunfire sounded like a jackhammer.
"I'm thinking, this work repair ... that was gunshot. I'm not used to that. I don't hear that around here," she said. "It's very, very unnerving that they're, they didn't catch and that this happened."
The armored truck company did not immediately respond to a request for comment.
The FBI is handling the investigation.
The US Bank will be closed for the remainder of Wednesday.