E.L. Konigsburg, the author of "From the Mixed-up Files of Mrs. Basil E. Frankweiler" and other classics of children's literature that have provided escape and companionship to generations of young readers, died Friday at Inova Fairfax Hospital in Falls Church, Virginia. She was 83.

Her death, of complications from a stroke, was confirmed by her son, Paul. Since her literary debut nearly half a century ago, Konigsburg had been celebrated as one of the finest storytellers of her era and genre.

Such was the reverence surrounding Konigsburg that she twice received the Newbery Medal, one of the highest awards in children's literature. She had the even rarer honor of being named a runnerup and winner in the same year, and for her first two published books.

In the late 1960s, then a Florida housewife with no agent, Konigsburg mailed to the Atheneum publishing house in New York her first manuscript — a story of friendship and witchcraft that became "Jennifer, Hecate, Macbeth, William McKinley, and Me, Elizabeth."

While waiting for its publication, she began "From the Mixed-up Files," the now-famous novel about sister-and-brother runaways who take up residence in New York City's Metropolitan Museum of Art and untangle the mystery of a beguiling marble statue of an angel. Both books were published in 1967, the first receiving the Newbery Honor and the second claiming the Newbery Medal.