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As the world mourns and reels from the death of "Sopranos" star James Gandolfini, new details continue to emerge about the Emmy-winning actor's sudden passing in Rome, Italy on Wednesday, June 19. At just 51 years old, the Italian-American icon was in Rome with his 13-year-old son, Michael, who had just graduated eighth grade. (Michael is the star's son with first wife Marcy Wudarski; he also leaves behind Liliana, his 8-month-old daughter, whom he shared with second wife Deborah Lin.)

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Gandolfini was also in the region for the Taormina Film Festival in Sicily; he had intended to attend the festival's closing ceremony this weekend and receive an award. Us Weekly can confirm that Gandolfini and his son were staying at the five-star Boscolo Exedra hotel in Rome, and is believed to have suffered a fatal heart attack in his room just before 10 p.m. local time. After a call was made from the hotel, he was taken by ambulance to the Umberto I general hospital. (He is believed to have died in transport in the ambulance.)

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"We can confirm that the 51-year-old man was brought here. Upon arrival at approximately 11pm, we found his heart had already stopped," a hospital spokesman tells Us.

TMZ reports that Gandolfini's first wife, Michael's mom, flew to Italy immediately to be by her son's side following the tragic incident.

About a week ago, Gandolfini "was in great spirits" hitting the red carpet solo at the the Stella by Starlight Gala (benefitting the Stella Adler Studio of Acting) in New York on June 10, an observer tells Us. "He was really there to support his friend Elaine Stritch. He was a bit goofy with the photographers, stood still for a moment on the carpet then stuck his tongue out at them!" the observer adds.

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An example of Gandolfini's magnanimous spirit was evident that night, the observer notes: "When he entered the dining room and walked to the head table, he realized there was no chair or place sitting for him by mistake. He was incredibly patient and gracious as he waited for the staff to scramble and add a chair," the witness says. "He just waited with a smile on his face and chatted with whoever approached him. He was a mensch!"

Tributes and remembrances continue pouring in for Gandolfini, whose career was defined by his portrayal of Tony Soprano in HBO's "Sopranos," widely considered one of the best TV shows of all time, and one of the most iconic characters in pop cultural history. (His long, illustrious film career includes such movies as "Zero Dark Thirty," "Killing Them Softly," "Where the Wild Things Are," "Romance and Cigarettes" and much more.)

Actress Lorraine Bracco, who played Tony's therapist Dr. Melfi, said in a statement: "We lost a giant today. I am utterly heartbroken."

"I have lost a brother and a best friend," Sopranos costar Stevie Van Zandt (who played fellow mobsters Silvio Dante) wrote on Facebook. "The world has lost one of the greatest actors of all time. Maureen and I send our deepest sympathy and love to Deborah, Michael, Lily, and all of Jimmy's family."

Added another Sopranos mainstay, Steven Schirripa says: "Jimmy was a dear friend and like a brother to me. He was a great actor and a great father. I will miss him terribly. I am very sad."

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Jeff Daniels, who performed on Broadway recently alongside Gandolfini in the acclaimed show God of Carnage, said, "If Broadway has a version of a guy you want in your foxhole, Jim Gandolfini was mine. During our time together in God of Carnage, we played 320 performances together. He didn't miss one. Sadly, I now miss him like a brother."

Actor and close friend Gilles Marini grieved via Facebook, and offered touching details on his friend's relationship with his little boy: "I am heartbroken. My bud James Gandolfini just died. Last Saturday he told me at our kids graduation chat he was so happy to go with his son to Italy. A boy trip! It was an honor to have met this man, such a great Dad! I spent so much time with James son teaching him soccer. I feel for that kid it must be so hard right now for little Micheal. Guys say a prayer for him and his family. This is going to be very difficult time for them. I am so so sad!."

Director Michael Roskam worked with the star on what would be his final film, "Animal Rescue," and tells Us in a statement: "It was such an honor to work with Mr. Gandolfini and nothing but a pleasure to see him perform. He was one of the greatest. I'm so sad and thinking about his family. I wanted to make him proud with the movie we made together and now it will be in his loving memory."


Check out photos from James' career

Stars react to his death