Michael Dwyer / AP Neil Diamond singing "Sweet Caroline" at a Boston Red Sox game on April 20.

Though a native New Yorker, Neil Diamond has become an inspirational figure in the city of Boston's recovery from the bombings at the Boston Marathon last week. Diamond's "Sweet Caroline" is a staple at the Red Sox' Fenway Park, and Saturday he made national news by being a surprise guest there to lead the crowd in a rousing rendition of the singalong at the team's first home game since the bombings.

With the singer already in the midst of penning new material, he tells Rolling Stone he's been moved to write about the tragedy. "I'm writing now and obviously affected by this situation in Boston, so I'm writing about it just to express myself," he says.

Watch: Neil Diamond leads "Sweet Caroline" singalong at Fenway

The Boston Marathon bombing was the most recent in a series of tragedies including the shootings in Aurora, Colorado and Newtown, Connecticut. The unnamed song from the Rock and Roll Hall of Famer will cover more than just the events in Boston. "It's like an infestation, and I'm writing about the general situation, not just about this bombing in Boston, but what we're going through with all of these tragedies – shootings and so on and so forth," he says.

While there's no timeline for the release of the song or new material, Diamond has the song on the fast track. When we spoke to him at the end of the week he said, "I spent the whole day recording it and I will spend tomorrow recording it. With a little bit of help from the man upstairs, I'll have it finished by the weekend."

"Sweet Caroline" plays at ballparks nationwide in Boston tribute

Following his back-to-back collaborations with Rick Rubin (2005's "12 Songs" and 2008's chart-topping "Home Before Dark"), Diamond has released a Christmas album, which included three original tunes, and the covers collection "Dreams." But he hasn't released predominantly original studio material since the Rubin collections.

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