WEST ALLIS, Wis. (CBS 58) -- The National Labor Relations Board (NLRB) has filed a complaint against Rogers Behavioral Health, alleging the treatment center illegally fired several employees who showed support for a union.

The complaint says Rogers fired three West Allis employees in February because they "supported and assisted the Union and engaged in concerted activities, and to discourage employees from engaging in these activities."

It goes on to say in April, three more workers were fired after letting the three previously fired workers into the treatment facility to participate in a unionization vote. The National Union of Healthcare Workers says this was their right, as these employees are still contesting the legality of their terminations.

The union says workers voted 54-4 in April to form unions at Rogers' West Allis and Madison treatment centers. 

The NLRB scheduled a hearing for the case in December.