In a minutes-long strike Sunday inside the world’s most-visited museum, 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 daylight heist about 30 minutes after opening, with visitors already inside, was among the highest-profile museum thefts in living memory and comes as staff complained that crowding and thin staffing are straining security.

The theft unfolded just 250 meters (270 yards) from the Mona Lisa, in what authorities 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.

Images from the scene showed confused tourists being steered out of the glass pyramid and adjoining courtyards as officers closed nearby streets along the Seine.

A lift — which officials say the thieves brought and which was later removed — stood against the Seine-facing façade, their entry route and, observers said, a revealing weakness: that such machinery could be brought to a palace-museum unchecked.