“They threatened a security guard and an elderly couple who were visiting the exhibit,” police told AFP. The thieves then “went to a glass display case where the artworks and documents were kept, placed them in a canvas bag, and walked out through the main entrance,” the same source said.

The municipality confirmed the theft at the Mario de Andrade Library, located in the center of the Brazilian metropolis.

According to news site G1, the suspects were identified through surveillance camera footage, and authorities are conducting an investigation to locate them.

Details about the specific works by Matisse (1869–1954) and Portinari (1903–1962) that were stolen have not yet been released.

The prints were part of the exhibition “From the Book to the Museum,” a collaboration between the library and São Paulo’s Museum of Modern Art (MAM). The exhibit, opened in October, showcased rare books and artworks from the 1940s and 1950s, and concluded on Sunday.

According to Folha de São Paulo, the stolen pieces include collages from Matisse’s Jazz album, published in France in 1947. It is estimated that only about 300 copies exist worldwide.

“Their cultural and artistic value is immeasurable,” said art critic and conservator Tadeu Chiarelli, quoted by the newspaper. “Their theft is very unfortunate,” he added.

The Jazz album is considered one of the “rare” and “fundamental” books of the period, paired in the exhibition with works by Brazilian artists and researchers of European modernism.

Around sixty drawings by Matisse — one of the most important modern artists of the 20th century — were sold for more than $2.5 million at a Christie’s auction in October, according to artnet.

Matisse’s auction record was set in 2018, when his 1923 painting Odalisque couchée aux magnolias sold for $80.8 million, also at Christie’s.

The five stolen Portinari prints — from one of Brazil’s most celebrated artists — illustrated the 1959 book Menino de Engenho (“The Plantation Boy”) by José Lins do Rego, according to municipal authorities.

“These are rare works; it is highly unlikely anyone will be able to buy them,” Chiarelli noted.

In 2007, a painting from Portinari’s O lavrador de café (“Coffee Plantation Worker”) series was stolen from the São Paulo Museum of Art (MASP), G1 reported.

The theft at the São Paulo library follows another high-profile heist reminiscent of a film plot — the recent robbery at the Louvre Museum, where jewels and a tiara worth at least €88 million were stolen. Four members of the alleged group have been arrested, but the stolen items — and the mastermind behind the crime — remain missing.