St. Charles County police officers responding to a report of a medical emergency found the legendary rocker unconscious about 12:40 p.m., authorities said.

Berry was pronounced dead about 45 minutes later after first responders failed to revive him, authorities said.

Bruce Springsteen was among a slew of rock giants who paid tribute to the man known as a founding father of the genre.

“Chuck Berry was rock’s greatest practitioner, guitarist, and the greatest pure rock ‘n’ roll writer who ever lived,” The Boss tweeted.

The Rolling Stones’ Mick Jagger offered a poetic take on Berry’s inimitable legacy.

“He lit up our teenage years, and blew life into our dreams of being musicians and performers,” Jagger said on Twitter.

“His lyrics shone above others and threw a strange light on the American dream. Chuck, you were amazing, and your music is engraved inside us forever.”

Even Bill and Hillary Clinton paused to honor Berry. “The man was inseparable from his music — both were utterly original and distinctly American,” they said. “He made our feet move and our hearts more joyful.”

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Remembering the life and career of rock ‘n’ roll icon Chuck Berry

In a way Berry wrote his own epitaph more than a half century ago in his 1958 hit “Johnny B. Goode.”

“He could play a guitar,” Berry wrote, “just like a-ringin’ a bell.”

The classic chords that propelled 1950s Berry hits like “Johnny B. Goode,” “Maybellene,” “School Day,” “Roll Over Beethoven” and “Sweet Little Sixteen” guided virtually every later rock guitarist, starting with the Beatles, the Rolling Stones, the Beach Boys and Eric Clapton.

“Chuck was probably the hardest person I’ve ever had to work with, including Mick Jagger,” Keith Richards said after organizing a 1986 show celebrating Berry’s 60th birthday. “But it was worth it, because he’s where it all started.”

Earlier that year Richards had inducted Berry as the first-ever member of the Rock and Roll Hall of Fame.

Berry was half of rock ‘n’ roll’s original twin pillars, next to Elvis Presley. He never sold as many records as Elvis, but his sound was just as distinctive and defining — and unlike Elvis, Berry was a lyricist and composer.

“You weren’t a rock guitarist,” wrote critic Dave Marsh, “if you didn’t know the riveting lick that kicks off ‘Johnny B. Goode.’ ”

Charles Edward Anderson Berry was born in St. Louis on Oct. 18, 1926. By the early 1950s he had been a GM worker, a cosmetologist and a three-year reform school student following a car theft and robbery spree.

He also had a wife, Themetta, and two daughters Darlin and Melody. The pair would have two more children, a daughter Aloha and son Charles Jr.

To earn extra money he played guitar at night — mostly jazz, though he was conversant with blues, rhythm and blues, country, popular and Latin music.

In the early 1950s he joined the Johnnie Johnson Trio, and in 1955 legendary bluesman Muddy Waters introduced him to Phil and Leonard Chess of Chess Records.

He reconfigured a country standard, “Ida Red,” into “Maybellene,” a humorous tale that likened a car chase between a Cadillac and a V8 Ford to the singer’s pursuit of his gal. “Maybellene” caught on with powerful rock ‘n’ roll deejay Alan Freed, who took half a writer’s credit and promoted Berry heavily on the radio, TV, stage and in the movies “Rock Rock Rock” and “Mr. Rock and Roll.”

In one memorable scene, Freed’s deejay character says his box-office receipts have been frozen, so he can’t pay the artists. Berry assures Freed he will play anyway, saying, “This one’s for rock ‘n’ roll.”

That scene became a classic because the real-life Berry would not play a note until his cash fee was secure in his hands.

Berry became a jukebox icon with a stream of radio hits about cool cars, the malt shop, high school, teenage music and teenage love.

Dismissed by adults as simplistic rhymes, they were some of the first rock ‘n’ roll poetry, full of great one-liners, wit, winks and even subtle social commentary.

Berry is also credited with popularizing the duck walk, an onstage move he initially invented in 1956 to “hide the wrinkles” in his lone suit.

And he’s rock ‘n’ roll’s only intergalactic star — a recording of “Johnny B. Goode” was included on the interstellar Voyager spacecrafts’ “Golden Record.”

“If you tried to give rock and roll another name, you might call it Chuck Berry,” John Lennon once said.

Berry was also one of the genre’s first bad boys. He was arrested in December 1959 for illegally bringing a minor suspected of being a prostitute across state lines. He was convicted in 1962 and served 18 months in prison.

Behind bars, Barry continued making music, writing the hits that would revive his career — “Promised Land,” “No Particular Place to Go” and “Nadine.”

By the 1970s he had become one of the first “rock ‘n’ roll revival” artists. He toured endlessly and hired local bands to back him — including, one night, a young Bruce Springsteen’s.

In 1972 Berry had his last radio hit, and his only No. 1, with the novelty song “My Ding-A-Ling.” By the end of the 1970s Berry had been invited by President Jimmy Carter to play at the White House and had served five months in prison for tax evasion.

He won a Grammy Lifetime Achievement Award in 1985 and was given a star on the Hollywood Walk of Fame in 1987.

Along the way he also sued the late John Lennon because Lennon pinched the line about “a flat-top” from Berry’s “You Can’t Catch Me” and used it in the Beatles’ “Come Together.”

Lennon settled by agreeing to record three Berry songs on his “Rock ‘N’ Roll” album.

His reputation took another hit in 1989 when he was sued by several women claiming that he had videotaped them in the bathroom of his restaurant near St. Louis. Berry eventually admitted to the pervy acts and paid restitution to 74 women.

Berry ultimately became wealthy, living with his family and a huge collection of expensive cars at his Wentzville, Mo., estate.

The tireless musician rocked and rolled into his 80s — even performing in South America four years ago at the age of 86.

Berry’s final New York performance was a 2011 New Year’s Eve show at B.B. King’s where he closed out the night with “Auld Lang Syne” and “Johnny B. Goode.”

Singer Martha Reeves was signing autographs after her own Saturday night performance at the famed Times Square venue when she learned of Berry’s death.

“It’s breaking my heart to hear this … I love Chuck Berry,” Reeves told the Daily News after her show. “He had a habit of getting all of his money and putting it in his guitar case and going on stage with it right there. I loved him for that. Best guitarist I’ve ever heard.”

Several rock lovers took a moment outside the famed Times Square venue to remember Berry.

“I’m absolutely sick about it,” said Janet Kent, 65, of the Upper East Side. “It was the foundation of my music-loving experience.”

A former jazz musician who identified himself as Oscar J. said he’d remember Berry for his stylish moves on stage.

“The duck walk. Putting the guitar behind his head. He was doing all that before Jimmy Hendrix,” Oscar said. “Not to say anything bad about Hendrix.”

Because Berry was reclusive, fans debated for decades whether his experiences with the law and the music business had embittered him.

He said in a 1986 interview he was not bitter, just private.

“I love rock ‘n’ roll,” he said. “It’s been very good to me and I think I’ve given something back.”