The Louvre remained closed Monday, a day after historic jewels were stolen from the world’s most-visited museum in a daring daylight heist that prompted authorities to reassess security measures at cultural sites across France.

The museum’s staff asked dozens of visitors who were queuing in front of the glass pyramid entrance to leave. In a message posted on social media, the Louvre said visitors who have booked tickets will be refunded. It did not provide additional details.

On Sunday, thieves rode a basket lift up the Louvre's facade, forced a window, smashed display cases and fled with priceless Napoleonic jewels, officials said. The theft occurred about 30 minutes after the museum opened, with visitors already inside, and was among the highest-profile museum thefts in living memory.

The stolen items included a crown worn by Empress Eugenie, a brooch of Empress Eugenie, and a crown worn by Queen Marie-Amelie

Archive footage showed the items as well as other jewels on display in the Galerie d’Apollon where they were taken.

The theft unfolded just 250 meters (270 yards) from the Mona Lisa, in what Culture Minister Rachida Dati described as a professional “four-minute operation.”

One object, the emerald-set imperial crown of Napoleon III’s wife, Empress Eugénie, containing more than 1,300 diamonds, was later found outside the museum, French authorities said. It was reportedly recovered broken.