The announcement marked the first breakthrough for police since thieves broke open an emergency exit and swiped the seven pieces on Oct. 16 in a late night raid at the Kunsthal gallery in Rotterdam.
It was the biggest art theft in more than a decade in the Netherlands. The stolen works have an estimated value of tens of millions of dollars if they were sold at auction, but art experts said that would be impossible following the theft.
"Three people have been arrested, but unfortunately we have not got back the paintings," Rotterdam Police spokeswoman Yvette van den Heerik told The Associated Press.
Police later said in a statement that the suspects were arrested as part of an ongoing Romanian investigation and not at the request of Dutch authorities.
Kunsthal spokeswoman Mariette Maaskant said gallery staff members are not yet breathing a sigh of relief. "There is no painting found yet," she said. "For us, that is the most important thing."
Romanian police spokeswoman Raluca Seucan declined to provide details of the case to the AP. Romanian news agency Mediafax reported that three Romanian suspects had been arrested Monday evening following a ruling from a Bucharest court. It gave no further details.
The heist at one of Rotterdam's landmark buildings, designed by local architect Rem Koolhaas, was low-tech but effective.
Two thieves forced their way into the gallery through a rear emergency door and snatched the paintings. Security cameras showed the thieves breaking in and fleeing within two minutes. They were gone by the time police, alerted by an alarm, arrived less than five minutes after the break-in.
The following morning, only white spaces on the wall and broken hanging wires were left.
The stolen paintings came from the private Triton Foundation, a collection of avant-garde art put together by multimillionaire Willem Cordia, an investor and businessman, and his wife, Marijke Cordia-Van der Laan. Willem Cordia died in 2011.
The stolen paintings were: Pablo Picasso's 1971 "Harlequin Head"; Claude Monet's 1901 "Waterloo Bridge, London" and "Charing Cross Bridge, London"; Henri Matisse's 1919 "Reading Girl in White and Yellow";Paul Gauguin's 1898 "Girl in Front of Open Window"; Meyer de Haan's "Self-Portrait," around 1890, and Lucian Freud's 2002 work "Woman with Eyes Closed."
Associated Press writer Alison Mutler contributed from Bucharest, Romania.