Actor James Gandolfini passed away on Wednesday while on vacation in Italy. The actor, best known for his starring role on the HBO series The Sopranos, was just 51 years old.

According to CBS News, hospital officials in Rome have confirmed that the actor died of cardiac arrest. Today.com reported the actor’s son, Michael, found him in the bathroom of their hotel on Wednesday. He was alive when the ambulance arrived but was declared dead about 40 minutes after being admitted to the hospital. The family was in town because Gandolfini was set to speak at the Taormina Film Festival in Sicily this weekend.

According to The New York Times, James Gandolfini was born in New Jersey in 1961 and went on to graduate from Rutgers University. However, he did not become interested in acting until he went to a class with a friend at the age of 25.

The actor made his film debut in a 1987 horror film called Shock! Shock! Shock!  From there, he appeared on Broadway in A Streetcar Named Desire and began a career as a character actor in several movies, but his big break truly came when he won the lead role in The Sopranos. Gandolfini played Tony, a mob boss and family patriarch in New Jersey. Per Reuters, Gandolfini earned three acting Emmys for the role, and the series won Best Drama in both 2004 and 2007.

James Gandolfini had remained busy after the series ended in 2007. Per EW.com, the actor recently appeared in the films The Incredible Burt Wonderstone and Zero Dark Thirty.

As Deadline notes, he also had several projects in development. He was set to reunite with Wonderstone co-star Steve Carell on Bone Wars, an HBO film about two paleontologists who helped discover over 160 dinosaurs. He was also set to appear in a limited-run series, Criminal Justice. The HBO event would have featured Gandolfini as an attorney who gets involved in the case of a Pakistani accused of murder. CBS had also given a script order to Taxi-22, a comedy that Gandolfini would have executive produced.

James Gandolfini leaves behind a wife, Deborah Lin, along with a son, Michael, and a baby daughter, Lililana.

Numerous celebrity tributes have already been pouring in. "He was a genius,” said Sopranos creator David Chase, per USA Today. “Anyone who saw him even in the smallest of his performances knows that. He is one of the greatest actors of this or any time. A great deal of that genius resided in those sad eyes.”

“I have lost a brother and a best friend,” added co-star Steven Van Zandt. “The world has lost one of the greatest actors of all time."

Here are some more Twitter tributes to James Gandolfini. "RIP James Gandolfini," wrote Olympic volleyball player Kerri Walsh Jennings. "Such a great actor. He was a star in a favorite film of mine ... True Romance. God bless JG and his loved ones."

"Thank you James Gandolfini for some of the most brilliant tv moments of all time," wrote singer Josh Groban. "So sad!!!"

"RIP James Gandolfini," wrote actress Olivia Munn. "An amazing actor who changed the game and raised the bar. You will be missed."

"James Gandolfini helped pave the way for great character actors to be leads, and for that all television lovers should be grateful," wrote Modern Family co-creator Steve Levitan. "RIP."

"RIP James Gandolfini," wrote Paris Hilton. "A brilliant actor. Too young to pass. My prayers go out to his family and friends."

You can watch James Gandolfini in the famous final scene of The Sopranos below.