Portillo's customers were evacuated from DeKalb avenue location of the popular restaurant in Sycamore earlier today because of a fire.

The Sycamore fire department was called to the scene and determined the fire was caused by a malfunction in an air conditioning unit. The Daily Chronicle reports that:

Sycamore Assistant Fire Chief Todd Turner said the culprit was a rubber belt from an air conditioning unit on the roof that snapped, wrapped around the motor and caught fire. Once the smoke detector went off, power to the unit was cut off.

The fire department was called just before 11 am and upon arrival it was determined that the fire was very small in nature.  Turner described the fire as a" pretty benign incident"

Customers who were at the restaurant when firefighters arrived, proceed outside the restaurant and enjoyed their lunch, and took the event in stride.

The Sycamore Portillo's is back open for business. The very temporary closure only affected a potion of Friday's lunch service.

Catch Mark Charvat on Q98.5 from 3 p.m to 7 p.m.. Follow him on Twitter, and Facebook