The Pirate Bay displays a "SITE DOWN" message including the statement that the police were in possession of valid search warrants alleging breach of copyright law, alternatively assisting breach of copyright law.
Swedish police have taken all servers of ThePirateBay into custody. Three people have been arrested, age 22, 24 and 28. They have not been charged, but are taken in because they the police suspect they have violated copyright laws. The persons are directly connected to TPB.org. 50 police men have worked on the case.
PirateBay.org, based in Sweden, has always been immune to anti-piracy drives and copyright lawsuits since their Stockholm-based servers provide only torrent files, which by themselves contain no copyright data - merely pointers to sources of the content.
This time however, people believe the raid was prompted by international political pressure by the US.