Severe storms and multiple tornadoes swept across the Midwest from Monday night into Tuesday morning, leaving over half a million energy customers without power and raising fears of flooding.

Illinois experienced nearly 330,000 power outages, Indiana had 188,000, and Iowa had close to 20,000, according to PowerOutage.us.

The National Weather Service in Chicago reported multiple tornadoes simultaneously, with a confirmed tornado in Des Moines, Iowa.

The Chicago weather service team had to take shelter as the storm hit around 10:30 p.m.

Chicago’s O’Hare Airport issued a ground stop, and local trains were canceled, NBC News has reported.

The weather service noted power flashes at the airport likely caused by tornadoes during some of the most intense storms the area has seen in years.

Meteorologist Kevin Jeanes from NBC Chicago remarked, “It’s been years and years since we’ve seen something like this.”

Written by B.C. Begley