Blanche Thebom, a mezzo-soprano who was discovered singing in a shipboard lounge as a teenager and went on to sing more than 350 performances with the Metropolitan Opera, died Tuesday at her home in San Francisco. She was 94.

Her death was confirmed by Roger Greenberg, a longtime friend.

In a field long dominated by Europeans, Thebom was part of the first, mid-century wave of American opera singers to attain international careers.

Associated with the Met from the mid-1940s to the mid-1960s, she was praised by critics for her warm voice, attentive phrasing and sensitive acting.

Thebom was best known for Wagner. She made her Metropolitan Opera debut in Philadelphia in November 1944 as Brangaene in an out-of-town production of “Tristan und Isolde”; the next month she appeared with the company in New York, singing Fricka in “Die Walkuere.”

Reviewing her “Walkuere,” a critic for The New York Times wrote that Thebom “scored an immediate success.”

At the Met, her other roles included Ortrud in Wagner’s “Lohengrin,” Azucena in Verdi’s “Trovatore” and Amneris in his “Aida,” and the title role in Bizet’s “Carmen.”

She also sang at Covent Garden and the Glyndebourne festival in England.