The storms included several tornados, strong winds reaching 120 miles per hour and about 80,000 lightning strikes.
The company said the storms caused severe damage to electrical infrastructure and broke down several poles and power lines.
ComEd executive vice president and chief operating officer Terence Donnelly said the company’s priority is to restore power quickly and safely to customers in the remaining affected areas.
"We appreciate our customers’ patience as we make repairs to our system following this damaging storm," Donnelly added.
ComEd provides services to about 3.8 million customers throughout Northern Illinois, or 70% of the state’s population.
The company, which manages 90,000 miles of powerlines in an 11,400-square-mile territory, has invested over $5bn in its electrical transmission and distributions system since 2001.
