A woman from Guatemala says she and her two U.S.-born children were held for nearly a week by customs agents in Detroit after a phone app's directions to the nearest Costco led them to the Ambassador Bridge.

The Michigan Immigrant Rights Center, the ACLU and Michigan Democratic Rep. Rashida Tlaib spoke on the detentions and alleged disappearance of immigrants in custody at the U.S.-Canada border.

It is the latest immigration twist in a growing legal — and political — showdown between two branches of government.