A powerful storm system swept through the Chicago region and northwestern Indiana on Tuesday, leaving more than 600,000 electricity customers without power as wind gusts exceeding 80 mph (128 kph) downed trees and damaged homes. Tornado warning sirens sounded across the area, all flights were temporarily halted at Chicago's two major airports, and Lake and Porter counties in Indiana along with Will County, Illinois, were among the hardest hit. The storms also reached Ohio, where a further 166,000 customers lost power and officials in Columbus sent government workers home early in anticipation of additional severe weather.