Best-selling author Vince Flynn, who wrote the Mitch Rapp counterterrorism thriller series and sold more than 15 million books in the U.S. alone, died Wednesday in Minnesota after a more than two-year battle with prostate cancer, according to friends and his publisher. He was 47.

Flynn was supporting himself by bartending when he self-published his first novel, "Term Limits," in 1997 after getting more than 60 rejection letters. After it became a local best-seller, Pocket Books, a Simon & Schuster imprint, signed him to a two-book deal -- and "Term Limits" became a New York Times best-seller in paperback.

The St. Paul-based author also sold millions of books in the international market and averaged about a book a year, most of them focused on Rapp, a CIA counterterrorism operative. His 14th novel, "The Last Man," was published last year.

He counted former presidents George W. Bush and Bill Clinton among his fans, as well as foreign leaders and intelligence community figures.

"As good as Vince was on the page -- and he gave millions of readers countless hours of pleasure -- he was even more engaging in person," said Carolyn Reidy, president and CEO of his publisher, Simon & Schuster. "Yes, we will miss the Mitch Rapp stories that are classic modern thrillers, but we will miss Vince even more."

Flynn died at a hospital in St. Paul, surrounded by about 35 relatives and friends who prayed the Rosary, said longtime family friend Kathy Schneeman. She said his deep Catholic faith was an important part of his character.

"That's what he would have liked. He talks about his faith just as much as he would talk about politics and current events with our group of friends," Schneeman said.

Flynn was born to an Irish Catholic family in St. Paul, the fifth of seven children. After graduating with an economics degree from the University of St. Thomas in 1988, he went to work as an account and sales marketing specialist with Kraft General Foods. That marketing background later came in handy as he promoted "Term Limits."

Wanting a new challenge, he quit Kraft in 1990 when he landed an aviation candidate slot with the Marine Corps, but he was later disqualified due to seizures he suffered following a childhood car accident. Thwarted from becoming a military aviator, he got the idea of writing thrillers.

"If (Tom) Clancy could do it, why can't I?" Flynn said in a 2005 interview with The Associated Press.

He went to work for the Twin Cities based commercial real estate company United Properties and started working on a book idea in his spare time. Two years later, he quit so he could devote more time to writing and moved to Colorado. He began working on what became "Term Limits," a story about assassins who targeted fat-cat congressmen.

A man of almost superhero powers, Mitch Rapp races the clock to foil terrorists' plans to detonate a nuclear warhead in Washington in "Memorial Day" (2004), battles terrorists who seize the White House and take hostages in "Transfer of Power" (1999) and is out for vengeance after a Saudi billionaire puts a bounty on his head in "Consent to Kill" (2005).

Flynn told the AP that with the fall of the Berlin Wall in 1989 and the end of the Cold War, he decided to write about terrorism.

"That's where the future's going. That's going to be the next big menace," Flynn recalled telling himself.

"He was so ahead of his time with what he was writing about terrorism and threats. His mind worked in a different way that most of us," said Frank Vascellaro, a WCCO-TV anchor who had been close friends with Flynn since just before "Term Limits" took off.

Vascellaro, who takes credit for having introduced Flynn to his wife, said the author's success was all the more remarkable given his struggles with dyslexia. "But at the same time it was a gift, because his brain did not think in the linear way 99 percent of the population sees things," he said.

Flynn became friends with Bush during one of his visits to Minnesota, Vascellaro said. As they shook hands on the airport tarmac along with dignitaries including the governor, the president told Flynn he was a big fan. Then an aide invited Flynn to ride downtown with Bush in the presidential limousine.

Vascellaro also recalled how Flynn met Clinton. He said Flynn was in New York with his wife when they saw a crowd around him. He pushed his way through to introduce himself, but Clinton replied, "I know who you are" and said he had read all his books.

Flynn was diagnosed with stage three metastatic prostate cancer in November 2010. The fatigue from his radiation treatments eventually made it difficult to focus on writing for more than an hour or two, and in October 2011, he reluctantly postponed publication for several months of his 13th book, "Kill Shot," which followed Rapp's adventures as he pursued those responsible for the bombing of a Pan Am flight over Lockerbie, Scotland, in 1988.

But he never expressed any bitterness about dying at such a young age and kept his faith, Vascellaro said.

"It was remarkable how much courage he showed in the face of adversity," he said. "I will remember that for the rest of my life."

Schneeman said Flynn had been working on his next book as recently as Valentine's Day, when she and her husband vacationed with the Flynns in Mexico. And development for a Mitch Rapp movie based on 2010's "American Assassin" remains on track, said Grey Munford, a spokesman for CBS Films, which plans to build an action-thriller franchise around the character. Bruce Willis has signed on to play Rapp's mentor, Stan Hurley. Munford said an announcement about the movie is expected soon.

Flynn is survived by his wife, Lysa Flynn, and three children.