United Airlines issued a nationwide ground stop for all of its mainline flights late Thursday after an emergency alarm at its Chicago operations center. "A fire alarm sounded at our operations ...

United Airlines says a fire alarm at the company’s operations center led to a brief nationwide ground stop of all United flights Thursday evening. The company said employees at the operations ...

Shares of Chicago-based United Airlines Holdings Inc. fell on news of the ground stop and closed down 2.5%. The Associated Press contributed to this report.

United Airlines issued a nationwide ground stop for all of its mainline flights late Thursday after an emergency alarm at its Chicago operations center. “A fire alarm sounded at our operations ...