A postal supervisor tied up two fellow workers in Harlem and stole $2,000 from them at knifepoint, sources said.

Ruth Sable, 41, robbed her colleagues at a postal facility on 158th Street at around 5:30 p.m., according to law-enforcement sources.

Two of the victims were tied up and robbed at knifepoint, while a third person was robbed without being bound, one source said.

Cops searched for Sable late Tuesday and eventually found her at her home in Middletown, where she was arrested. Charges were pending.