PARIS — The Louvre Museum remained closed on Monday following a daring jewel heist that occurred the previous day. Thieves stole historic jewels from the world’s most-visited museum in a brazen operation that has prompted authorities to reevaluate security measures at cultural sites across France.

On Sunday, just 30 minutes after the museum opened, a group of robbers used a basket lift to access the building. They forced a window, smashed display cases, and fled with priceless Napoleonic jewels. The theft took place near the Mona Lisa, in what Culture Minister Rachida Dati described as a professional operation lasting only four minutes.

The museum's staff evacuated dozens of visitors waiting outside the glass pyramid entrance. In a social media post, the Louvre announced that it would refund tickets for those affected but did not provide further details.

French Justice Minister Gérald Darmanin acknowledged security failures, questioning why the windows were not secured and how a basket lift was allowed on a public road. "Having been interior minister, I know that we cannot completely secure all places, but what is certain is that we have failed," he said on France Inter radio.

Culture Minister Dati confirmed that investigators are examining evidence collected at the scene, including a motorcycle with a license plate. She praised security officers for preventing the basket lift from being set on fire, which allowed authorities to gather crucial evidence.

Dati also highlighted a decade-long plan called the "Louvre New Renaissance," which aims to improve security and modernize the museum's infrastructure. The plan, which has a budget of 700 million euros ($760 million), is intended to accommodate the museum's growing visitor numbers and enhance security measures.

The heist occurred around 9:30 a.m. on Sunday. The thieves targeted the gilded Apollon Gallery, where the Crown Diamonds are displayed. They smashed two display cases and escaped on motorbikes. Fortunately, no injuries were reported during the incident.

Eight items were stolen, including a sapphire diadem, necklace, and earring linked to 19th-century queens Marie-Amélie and Hortense. Other stolen items included an emerald necklace and earrings belonging to Empress Marie-Louise, a reliquary brooch, and Empress Eugénie’s diadem, which features over 1,300 diamonds. One of the stolen items, the emerald-set imperial crown of Empress Eugénie, was later found outside the museum.

As the investigation continues, the Louvre remains closed, and officials are working to enhance security protocols to prevent future incidents. Interior Minister Laurent Nunez has ordered a reassessment of security measures at museums and cultural sites across the country.