Best-selling author Tom Clancy died in Johns Hopkins Hospital in Baltimore after a brief illness on Tuesday, Oct. 1. He was 66 years old.

According to The New York Times, president of Putnam Books Ivan Held confirmed his death. No cause of death was provided.

Born in Maryland in 1947, Clancy was best known for his detailed spy and military thrillers that inspired four movies, The Hunt for Red October, Patriot GamesClear and Present Danger, and The Sum of All Fears, which grossed about $800 million.

Clancy was the second of three sons to Tom Clancy Sr. and Margarette Anne Muggins Clancy.

Clancy attended Loyola Blakefield, an all boy’s catholic school, in Towson, Maryland. He then attended Loyola College, graduating in 1969.

He married his first wife, Wanda, soon after in 1970. They had four children together before their divorce in 1998. One year later, Clancy married 32-year-old Alexandra Marie Llewellyn, a fellow writer.

The Hunt for Red October was Clancy’s first novel following the suspenseful adventure of Soviet submarine captain Marko Aleksandrovich and CIA analyst Jack Ryan. Clancy sold his book to the Naval Institute Press for just $5,000. It unexpectedly landed in the hands of former President Ronald Reagan and instantly became a best seller. Reagan raved about the book, stating that he could not put it down. The Hunt for Red October made over $5 million.

More than 100 million copies of his books have been printed, and 17 have earned the No. 1 spot on The New York Times’ best-seller list.

The ex-insurance salesman also co-founded the video game developer Red Storm, which created thrilling, life-like shooter games like the Splinter Cell, Ghost Recon, and Rainbow Six series. His games were so realistic that the government approved them for military training.

Fans can expect Clancy’s latest and final novel, “Command Authority,” to be printed on Dec. 3.