July 12 (Reuters) – Tornadoes and thunderstorms battered the greater Chicago area on Wednesday, temporarily forcing O’Hare and Midway airports to halt all air traffic, officials said, as tornado sirens echoed through the third biggest U.S. city. At least eight tornadoes touched down in four counties in northeastern Illinois, including four in Cook County, which is home to Chicago, as officials warned people to take shelter. All departures of commercial flights into O’Hare and Midway airports were grounded, and outgoing flights from the two airports were delayed, the U.S. Federal Aviation Administration reported. More than 300 flights in and out of O’Hare and another 32 in and out of Midway were canceled, according to FlightAware. Off-site air traffic controllers assumed control of the airspace as the on-site controllers needed to evacuate the towers at O’Hare and Midway, the FAA said. Normal operations resumed after the storms passed, the FAA said. Trees were uprooted and roofs blown off in the Cook County town of Countryside, and car windows were blown out in La Grange, the National Weather Service reported. Tree and roof damage was also reported from several other twisters, the service said. One photo posted on social media showed a cinder block building collapsed in what appeared to be an industrial district of McCook, about 15 miles (24 km) southwest of Chicago.w