Emergency lights on at Willis Tower but no word on when full power might come back after weekend flooding

CHICAGO (WLS) -- Some lights were on at the Willis Tower early Friday morning, but full power still has not been restored to Chicago's tallest building after weekend flooding knocked it out.

ComEd said crews have been testing the emergency lights, and they're still working to restore power at the tower.

Willis Tower was still without power Thursday as crews work to assess the damage after a substation flooded due to heavy rain earlier this week.

ComEd said as of Wednesday night crews were able to pump out all 4 feet of water that flooded the tower's basement and repairs had begun.

Officials said there is no estimate yet on when power will be restored.

RELATED: High water levels continue to plague Willis Tower; close roads in city, suburbs

ComEd is working with building management, Chicago fire and the city of Chicago to reenergize the Willis Tower safely, officials said.

Crews will have to restore power to the high-rise in phases, a ComEd spokesperson said.