The fire started as customers inside were being served. Patrons and employees ran outside to escape the flames before plumes of smoke began billowing out of the steakhouse.
There was a significant Chicago Fire Department presence blocking off southbound lanes on State Street just north of the river, snarling rush hour traffic on a Friday afternoon.
"It smelled like there was burning fat from the fries or something from the kitchen," said Veronika Kaisers, a tourist from Germany who was about to enter the restaurant when the fire broke out.
One firefighter suffered injuries and was seen on a stretcher, but he did not have an oxygen mask on. Chicago fire officials said there was a lot of smoke in the restaurant's ventilation system but did not say if the firefighter was suffering from smoke inhalation. He was taken to Northwestern Memorial Hospital for treatment.
The cause and where the fire started are still under investigation.