Masterpieces by Rubens and Tintoretto were among 15 artworks stolen 'to order' by masked robbers from a museum in Verona, the city's mayor said Friday, November 20, according to AFP.

Three men dressed in black entered the Castelvecchio museum in northern Italy at the evening change of guard on Thursday, tying up and gagging the site's security officer and a cashier before nabbing the paintings.

Their haul included "Portrait of a Lady" by Flemish Baroque painter Peter Paul Rubens and "Male Portrait" by Venetian artist Tintoretto, as well as works by Pisanello, Jacopo Bellini, Giovanni Francesco Caroto and Hans de Jode.

The museum told art investigators the works were worth an estimated 15 million euros ($16.05 million), adding that it looked like the job had likely been masterminded by a private collector.

"Someone sent them, they were skilled, they knew exactly where they were going," mayor Flavio Tosi said, adding that 11 of the paintings stolen had been masterpieces while others were more minor works.

Roberto Bolis from the council's press office said the museum had 24-hour security but the robbery had been planned so that the thieves arrived after the building emptied but before the alarms had been activated.

"We don't yet know if they were armed, or whether they took the security officer's weapon," he said, adding that both the guard and cashier were in shock and were being debriefed by investigators.