Twenty-five workers who clean Target stores are complaining that they are locked in the buildings during overnight shifts and have to find a manager to unlock a door if they need to exit, the Star Tribune reports. They consider it a fire risk, among other objections.

The workers have filed a grievance with the federal Occupational Safety and Health Administration, also alleging in a separate complaint that they have not been properly trained in how to handle cleaning chemicals, the newspaper reports.

The companies that hired the workers are Carlson Building Maintenance of White Bear Lake and Prestige Maintenance USA of Plano, Texas.

About two dozen cleaning workers gathered outside Target's corporate headquarters in downtown Minneapolis Thursday in an effort to draw attention to the issues, the Pioneer Press reported.