PARIS -- The Louvre Museum in Paris was closed to the public on Sunday "for exceptional reasons" following a robbery in which several items of great historical value were stolen, French authorities said. No injuries were reported.

According to initial reports, masked perpetrators allegedly entered the museum through an area under renovation, used a freight elevator to reach the targeted room, and broke windows to gain access.

French Interior Minister Laurent Nunez, who visited the scene, described the stolen artifacts as being of "inestimable" heritage value. Investigators from the Paris police headquarters have secured the site and launched a technical investigation. The Louvre and the Ministry of Culture are compiling a detailed list of the stolen items and assessing their value.

Local media reported that three or four thieves took nine pieces of jewelry from the collection of Napoleon and the Empress and remain at large, while a crown from the same collection was reportedly found broken outside the museum.

Culture Minister Rachida Dati told television network TF1 that "a piece of jewelry was found near the Louvre and is currently being evaluated," adding that "organized crime today targets works of art" and that "museums have become targets."

The Louvre's management had earlier warned of infrastructure issues affecting the conservation and security of artworks, pending a major renovation program.

Police have appealed to the public for information. The museum has not yet announced a reopening date.