James Gandolfini, the Emmy Award-winning actor best known for his work on HBO's The Sopranos, has died in Italy, HBO confirms. He was 51.

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The star is said to have suffered a sudden heart attack while on vacation on Wednesday, June 19.

Gandolfini won three Emmys for his portrayal of mob boss Tony Soprano. More recently, he appeared in Zero Dark Thirty and The Incredible Burt Wonderstone. He had been working on the upcoming crime thriller Animal Rescue and the TV series Criminal Justice, which was picked up by HBO in May.

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Actress Rose McGowan, who did a USO tour with the actor, was among the first to express her condolences over Gandolfini's death. "I am heartbroken about James Gandolfini," she tweeted. "He was a gentle giant and great man...I loved him."

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Gandolfini is survived by his wife, Deborah Lin, and two kids, son Michael and daughter Liliana.

This article originally appeared on Usmagazine.com: James Gandolfini Dead: Sopranos Star Dies of Heart Attack at 51