Two thieves broke into the Renoir Museum in Cagnes-sur-Mer on the French Riviera and stole four paintings by renowned French artist Pierre-Auguste Renoir in a heist that lasted less than three minutes.

The stolen works were valued at about €9 million ($10.5 million), but police quickly arrived after the museum’s alarm was triggered, forcing the thieves to flee.

Two paintings, “Portrait of Madame Pichon” and “Coco Reading,” were abandoned in the museum garden and recovered, while “Portrait of Madame Colonna Romano” and “Young Woman at the Well” remain missing.

Authorities believe the thieves were well-equipped and had knowledge of the museum, entering through a window after cutting through a fence and targeting the most valuable artworks, the AP has reported.

The theft has renewed concerns about security and funding at smaller French museums, while investigators warn that the missing Renoirs will be extremely difficult for criminals to sell because of their international recognition.