The site was frequently visited in France and had 5 million members, however it was still relatively unknown in Sweden.
T411 went offline on Sunday evening (June 25), prompting speculation in the tech world over whether this was due to maintenance or a police swoop.
The Swedish police confirmed that the men suspected of running the site had been arrested on suspicion of copyright infringement and money laundering.
"It's an ongoing operation which I am leading in cooperation with the French authorities. There is a parallel effort in France. Our investigation is about questioning the persons and sending evidence to the French authorities," District Prosecutor Henrik Rasmusson told Swedish daily Dagens Nyheter.
The police added that the men were not Swedish citizens, but where in the country legally. The file sharing site was created in 2006 and was called QuebecTorrent, after it went through several domain changes before it was reintroduced as T411 in 2011.
The site was being watched by the authorities, according to sources, as complaints had come in from musicians and composers, as well as France's anti-piracy organization, ALPA.
A 2015 US government report by the Recording Industry Association of America (RIAA) listed T411 as one of 57 "notorious pirate sites" in the world.