A valuable drawing by the famous artist Pablo Picasso has been stolen from an art gallery in the western U.S. city of San Francisco.

Gallery owners told police the brazen theft happened Tuesday, when a man in dark glasses walked off with the drawing, called “Tete de Femme,” in the middle of the day while the gallery was open to the public.

The man apparently fled with the work of art in a taxi.

Other works by equally famous artists, including Marc Chagall, Salvador Dali and Joan MIro, were left untouched in the gallery.

Police are asking the public, and especially art dealers, to keep an eye out for the Picasso original, hoping to catch the thief if he tries to sell it.