Thieves stole three paintings from the Renoir Museum on the French ‌Riviera early on Tuesday, the local mayor said.

The raiders broke into the museum ‌a little before 6 a.m. and took four ‌paintings, ⁠Cagnes-sur-Mer mayor Bryan Masson said on his ⁠Facebook page.

Police spotted the thieves and gave chase, during which they dropped one painting but escaped with the other ​three, he said.

“Attacking ‌the Renoir museum is attacking a part of the history and heritage of Cagnes-sur-Mer. These actions are particularly serious,” Mr. Masson said in his message.

The ‌museum was created in 1960 in ​the mansion of the impressionist painter Pierre-Auguste Renoir on a hill in Cagnes-sur-Mer, near ⁠Nice, where he died in 1919. The collection on display in the museum includes 13 paintings ‌from the master and some 40 sculptures, furniture and photographs.

Mr. Masson did not identify the paintings that were stolen. Renoir’s most valuable works have fetched dozens of millions of dollars at auctions in the past.

Art thieves in Europe are committing ‌more violent robberies and specialist gangs have been replaced by ​ad hoc opportunists recruited through social media, pan-European police body Europol said last month.

The ⁠heist at the Louvre Museum in Paris in ⁠October last year was a prime example of this, Europol said, as the thieves threatened ‌guards and visitors and stole €88 million ($102.3 million) worth of jewels, such as Empress Eugenie’s tiara.