Two businesses in the ByWard Market have been damaged by an early morning electrical fire.

A fire broke out in the basement of these Byward Market shops. (Marc Messier/Ottawa Fire Services)

The fire started in the shared basement of the Allegro and Bang On clothing stores on William Street at about 6:45 a.m., causing extensive smoke, water and fire damage.

Next door, the Crocs shoe store and the Ottawa Festivals office also sustained smoke damage.

Other businesses had to open late as fire crews worked in the area, as owners cringed at the thought of needing to close down during the summer months.

Andrea Corey, who used to manage the two damaged stores and now runs the clothing store Neon on nearby George Street, said the fire is sad, especially given the timing.

"This is when all of the little shops around here make their money," she said.

William, York and George Streets were all closed while the fire was being dealt with.

Ottawa Fire Services said a contributing factor to the fire was that an extension cord was being used for permanent wiring.

Fire officials said in a statement that people should use extension cords as a temporary connection only, that extension cords should not be linked together, and that air conditioners and other heavy appliances should be plugged directly into an outlet.

People should also avoid running cords under carpets or in other locations where they can be damaged, the statement said.