James Gandolfini, best known for playing Tony Soprano on HBO’s hit series The Sopranos, has died at age 51, according to his managers and to an HBO spokesperson. Gandolfini was reportedly on vacation with his family in Rome, Italy when he suffered a massive heart attack.

Gandolfini was born in 1961 in New Jersey and began his acting career in his 20s. He spent most of his career as a character actor, usually playing tough-guy characters. He gained widespread notoriety when he landed the role of mob boss Tony Soprano in The Sopranos in 1999. The Sopranos ran for six seasons before concluding in 2007. He has also had a successful Broadway career, most recently starring in God of Carnage.

Gandolfini’s managers, Mark Armstrong and Nancy Sanders, released a statement saying, “It is with immense sorrow that we report our client James Gandolfini passed away today while on holiday in Rome, Italy. Our hearts are shattered and we will miss him deeply. He and his family were part of our family for many years and we are all grieving.”

Meanwhile, HBO also released a statement: “We’re all in shock and feeling immeasurable sadness at the loss of a beloved member of our family. He was a special man, a great talent, but more importantly a gentle and loving person who treated everyone no matter their title or position with equal respect. He touched so many of us over the years with his humor, his warmth and his humility. Our hearts go out to his wife and children during this terrible time. He will be deeply missed by all of us.”

As you might expect, the news has spread quickly across social media. At the time of this writing, “James Gandolfini,” “RIP,” “Tony Soprano,” and “Sopranos” are all trending on Twitter. Here’s a sampling of what people are saying:

Wow. RIP James Gandolfini. His talent brought me many hours of compelling entertainment. Sad for his family and friends.

— Richard Marx (@richardmarx) June 20, 2013

Sad to hear about James Gandolfini passing away. 51 is young and he was really talented.

— Jon Acuff (@JonAcuff) June 20, 2013

I am shattered by the news of the loss of my longtime hero and new friend, James Gandolfini. My thoughts and prayers go out to his family.

— Brian Baumgartner (@BBBaumgartner) June 20, 2013

I am shattered by the news of the loss of my longtime hero and new friend, James Gandolfini. My thoughts and prayers go out to his family.

— Brian Baumgartner (@BBBaumgartner) June 20, 2013

The thing about our random James Gandolfini 2:30 a.m. bar encounter: He was OUT OF HIS WAY friendly. And it made our months that he was.

— Mike Ryan (@mikeryan) June 20, 2013

Very sad to hear of James Gandolfini's passing! I think Tony Soprano would have had this reaction to death! pic.twitter.com/FlWCCCb2xF

— Jim Michaels (@TheJimMichaels) June 20, 2013

James Gandolfini was not Tony Soprano…he was a father, husband and a fellow human being, gone far too soon. RIP

— Jennifer (@hipchkk) June 20, 2013

Gandolfini leaves behind a wife, Deborah, a 9-month-old daughter, Liliana, and a son, Michael.