CHICAGO (CBS)– Flooding caused a power outage at the Willis Tower overnight.

Building owners said flooding on Lower Wacker Drive knocked out the electricity.

“We are working with officials from Willis Tower and the city of Chicago to assess the situation to determine a way to return electric service to the building as quickly and safely as possible,” a ComEd spokesperson said in a written statement. “Willis Tower is currently the only building affected by the flooding.”

This is a developing story.