AMSTERDAM — Thieves broke into a Rotterdam museum on Tuesday and walked off with works from the likes of Picasso, Monet, Gauguin, and Matisse potentially worth hundreds of millions.

Police have not said how the thieves pulled off the early-hours heist, but an expert who tracks stolen art said the robbers clearly knew what they were after. ‘‘Those thieves got one hell of a haul,’’ said Chris Marinello, who directs the Art Loss Register.