The clerk's office was forced to process sticker purchases manually and people could buy them, as long as it was not with a credit card.
The power failure began around 2 o'clock and affected the internal internet connection, including email and shared files.
By about 4 p.m. Thursday afternoon, the power failure was fixed.
A spokesperson for the mayor's office tells the Sun-Times that she was positive the problem had nothing to do with hacking.
