City prosecutor Laure Becquau said in a statement that all four—two men, aged 38 and 39, and two women, aged 31 and 40—are from the Paris region.
Tuesday's arrests are in addition to the four people already charged in the case. According to the statement, three men and one woman have been charged with organized theft and criminal conspiracy to commit a crime.
Last month, the group circumvented security systems and used power tools in broad daylight to steal jewelry worth millions from the famed Paris museum. Authorities told NBC News that they ultimately escaped with royal jewels once worn by France's queens and empresses: a necklace, earrings, and a tiara from the Queen Marie-Amélie and Queen Hortense collections; and a brooch, bodice bow, and a tiara from the Empress Eugénie collection.
The stolen jewels are valued at approximately $102 million and have not yet been handed over to Paris authorities.
At least two of the stolen items, including Empress Eugénie's crown, fell while being evacuated, providing clues to the group suspected of the theft.
The thieves, described by French Interior Minister Laurent Nuñez as "experienced," used power tools, including disc cutters, to break through a window at the Galerie d'Apollon, the prosecutor's office said. A truck-mounted crane lift was outside the window and was brought in to assist in the theft, which occurred at 9:30 a.m., when the museum was opening.
Officials said the theft took just seven minutes and forced the museum to close for the day—a rare occurrence.
Before the theft, the Louvre had been ordered by a French auditor's court to speed up modernizing its security systems. According to a report, the process has been delayed, and was expected to be completed by 2032.