The incident ended with police cutting the alleged bank robber, whose name was not reported, out of the air duct early Sunday, the Chicago Tribune reported.
The suspect allegedly robbed a Bank of America around 2 p.m. Saturday, said Oak Lawn Police Department Division Chief Michael Kaufmann.
FBI spokeswoman Joan Hyde said the man walked into the bank carrying a handgun and announced a robbery. He then left the bank on foot with an undisclosed amount of cash.
SWAT members from the South Suburban Emergency Response Team, Cook County Sheriff and FBI assisted by Chicago police found the suspect "hiding in an air duct so tight he had to be cut out of the duct. The location was a second floor ceiling in the middle of the center," Kaufmann said in a e-mail press release early Sunday morning.
The suspect was taken into custody without physical resistance, Kaufmann said.