Require a manager be on duty until your assignment is completed. The ELM only states Saturday, in small offices, that a manger doesn't have to be in the facility. I'm assuming no manager is in the office? So grieve it, but make damn well sure your steward cites the agreement in the ELM and find incidents where an rca died on route on a Saturday when no manager was present. Also file a 1767 safety violation, stating you dont feel safe without someone watching you-cite deaths.