CHICAGO (AP) — Southwest Airlines announced Friday that it has cancelled all of its fights in and out of Midway International Airport, days after federal authorities closed the airport's control tower after technicians tested positive for the coronavirus.

“We have ceased operations at the Chicago Midway airport due to the closure of the FAA ATC tower in the Chicago area,” Southwest Airlines spokesperson Ro Hawthorne wrote in an email.

The airlines' move resulted in more than 173 canceled flights on Friday.

The Federal Aviation Administration closed Midway's control tower on Tuesday after the federal agency said "several" technicians tested positive for coronavirus. The FAA said in a statement that the airport remained open and operations would continue at a reduced rate until controllers and technicians have a safe working environment.

As of Thursday, Illinois public health officials have said that 422 people statewide have tested positive for COVID-19, the disease caused by the virus, and that four people have died.

Illinois officials were scheduled to provide an update Friday on the coronavirus.

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