From a new report:

Actor James Gandolfini died suddenly in Italy after a suspected heart attack. He was 51. Gandolfini will be forever known for his portrayal of mob boss Tony Soprano on the seminal HBO series The Sopranos, which won him three Emmy Awards. He remained in business with the pay cable network and was in pre-production on a new limited series, Criminal Justice, one of several projects he had in the works.

http://www.nydailynews.com/entertainment/james-gandolfini-dead-51-article-1.1377435