A violent storm struck Chicago and its suburbs Monday morning, resulting in power-outage for over 800,000 ComEd customers.

The senior vice president of customer operations of ComEd Fidel Marquez said it was the “largest storm we’ve ever experienced in terms of the number of customers affected.”

ComEd, in addition to its 480 crews in the area, had to call additional workers from nearby states to restore power. Workers from Iowa, Missouri, Wisconsin, and Pennsylvania have reportedly been called to help, according to Chicago Sun-Times.

Marquez added that it may take days before everyone can get their power.

The storm, consisting of winds 70 to 80 mph, hail, and heavy rain, have caused flights to be cancelled, knocked down trees, stopped the traffic, and caused damage to some buildings. There are no reported deaths at the moment, although some minor injuries occurred.

Some workers in Palos Hills were hurt when the wind struck down the tent during its four-day festival, according to a Chicago Sun-Times report.

Chicago Tribune has also reported “more substantial” injuries that have taken place in Cook County.

The storm is currently said to be moving east at 65 mph toward Indiana and no further damage will take place in Chicago.