Security workers are staging a one-day strike at O'Hare International Airport in a national protest over labor practices.

More than 150 people at O'Hare are trying to form a union. One worker said that she was fired by Universal Security, which is subcontracted by the Chicago Department of Aviation, for trying to organize. 

Workers -- which includes more than 2,000 sub-contracted wheel chair attendants, cleaners and baggage handlers-- at one of the busiest airports in the U.S. participated, reported ABC7 Chicago.