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Muhammad Ali, the legendary boxer who proclaimed himself “The Greatest” and was among the most famous and beloved athletes on the planet, died Friday in Arizona, a family spokesman said.

A public memorial is scheduled for Friday at 2 p.m. ET at the Yum Center, a 22,000-seat basketball arena in the city where Ali grew up and began his amateur career as a 12-year-old.

Information on tickets will be released later. The service will be streamed live on the website for the Muhammad Ali Center.

Former President Bill Clinton, longtime sportscaster Bryant Gumbel and comedian and close Ali friend Billy Crystal will be among those delivering eulogies, spokesman Bob Gunnell said

The immediate family will have a private gathering Thursday.

“Muhammad Ali was truly the people’s champion, and the celebration will reflect his devotion to people of all races, religions and backgrounds,” the family said in a statement.

Before the service, Ali’s body will be driven through the streets of Louisville. He will be interred at Cave Hill Cemetery.

Ali, 74, died Friday night at 9:10 MT, the result of septic shock due to unspecified natural causes, Gunnell said.

Ali had been at HonorHealth Scottsdale Osborn Medical Center in Scottsdale since Thursday with what spokesman Bob Gunnell had described as a respiratory issue.

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Ali’s daughter Hana Ali said her father was a “humble mountain.”

After Ali’s organs failed, his daughter wrote in the tweet, his heart continued to beat for another 30 minutes: “A true testament to the strength of his Spirit and Will!”

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Longtime Ali friend John Ramsey, who works for WAVE in Louisville and who has a radio show on ESPN, was at the hospital with Ali’s family when the boxing legend died.

“When he came into the hospital, we thought, ‘OK, it will be a brief stay’… I think it took a turn for the worse,” he told CNN’s Dan Simon. “But it was unexpected.”

Ramsey said Ali’s wife, Lonnie, called him Friday morning, saying Ali’s health was deteriorating.

“She said ‘You might want to come out,’ which I decided to do,” he said.

Tributes from around the world

While touching tributes to Ali were pouring in from world leaders, fellow athletes and just regular folk, the boxing great had already addressed how he wanted the world to think about him after his death.

In his book “The Soul of a Butterfly: Reflections on Life’s Journey,” Ali said he wanted to be remembered as “a man who won the heavyweight title three times, who was humorous, and who treated everyone right. As a man who never looked down on those who looked up to him, and who helped as many people as he could. As a man who stood up for his beliefs no matter what. As a man who tried to unite all humankind through faith and love.”

He added, ” And if all that’s too much, then I guess I’d settle for being remembered only as a great boxer who became a leader and a champion of his people, And I wouldn’t even mind if folks forgot how pretty I was.”

President Barack Obama said he and first lady Michelle Obama mourn Ali’s passing.

“But we’re also grateful to God for how fortunate we are to have known him, if just for a while; for how fortunate we all are that The Greatest chose to grace our time,” the Obamas said in a statement.

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His hometown pauses to reflect

Louisville Mayor Greg Fischer, at a ceremony honoring Ali on Saturday, said the boxer “lived a life so big and bold, it’s hard to believe that any one man could do everything he did, could be all the things that he became in the course of just one lifetime.”

Fischer added, “Muhammad Ali belongs to the world, but he only has one hometown. The ‘Louisville Lip’ spoke to everyone, but we heard him in a way no one else could – as our brother, our uncle, and our inspiration.”

People started lining up at 2 a.m. Saturday to see his childhood home, which opened as a museum in early May.

Memorials piled up on the front steps and guests paid their respects inside to Ali’s brother, Rahaman Ali.

In an interview with CNN, Ali’s brother Rahman Ali said he was sad because “I won’t see my brother in the flesh anymore. It’s traumatic, I can’t see him anymore. Consolation is that I’ll see him in heaven.”

The brother recalled his last words to Ali in a phone conversation: “‘I will see you tomorrow, Champ. Take care of yourself.’”

Don King, the boxing promoter who was every bit as brash as Ali, told CNN that in his mind Ali will never die.

A beekeeper who was called out to the site called it an “exceptional coincidence.”

“Swarms happen all the time in Louisville, and everywhere, in May and June when bees reproduce,” backyard beekeeper Kevin McKinney said.

However, Donald Lassere, president and CEO of the Muhammad Ali Center, had a more cosmic interpretation.

“The Muhammad Ali Center has always experienced what we have come to know as, ‘Muhammad Magic,’ but I cannot even conceive as to the genesis of those bees,” Lassere said.

‘A true great has left us’

Don King, the boxing promoter who was every bit as brash as Ali, told CNN that in his mind Ali will never die.

“His spirit will go on forever,” he said. “He’s just a great human being, a champion of the people, the greatest of all time.”

Even as the former champ battled Parkinson’s disease, he had the same love for life and people, King said. Parkinson’s, which primarily affects a patient’s movement, is a “progressive disorder of the nervous system,” according to the Mayo Clinic.

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The Ali sense of humor was displayed in an old photo tweeted by Oscar De La Hoya, who won titles in six weight classes.

“I love this photo of my father and my daughter Sydney when she was a baby! Thanks for all the love and well wishes. I feel your love and appreciate it!!” Laila Ali, herself a former world champion boxer, wrote.

George Foreman, who Ali defeated in 1974 for the world heavyweight title, wrote on Twitter, “It’s been said it was rope a dope Ali beat me with. (N)o (it was) his beauty that beat me. Most beauty I’ve know(n). loved him.”

Famed promoter Bob Arum wrote on Twitter: “A true great has left us. @MuhammadAli transformed this country and impacted the world with his spirit.”

Mike Tyson, the youngest heavyweight champion in history, said, “God came for his champion. So long great one. @MuhammadAli #TheGreatest #RIP.”

Champion for Parkinson’s families

In recent years, Ali had largely stayed out of the public spotlight. In his last known appearance, he appeared at a Parkinson’s fundraiser April 9 in Phoenix, according to the Arizona Republic. A photo posted by the newspaper showed Ali wearing dark sunglasses.

Ali was known not only for his athletic prowess but also for his social activism.

He was born in Louisville, Kentucky, as Cassius Clay in January 1942. He began boxing as an amateur when he was 12 years old and in 1964 became heavyweight champion with a knockout of Sonny Liston. That year he joined the Nation of Islam and changed his name.

In 1964 he became heavyweight champion (the youngest ever at the time) with a surprising knockout of Sonny Liston. That year he joined the Nation of Islam and changed his name.

Ali’s sparkling career was interrupted for 3½ years in the 1960s when he refused induction into the U.S. Army during the Vietnam War and was convicted of draft evasion. The Supreme Court overturned the conviction.

Ali was prepared to go to prison, King said.

“He stood his ground on who he was,” King said. “He’d rather go to jail than break what he believed in.”

During his boxing hiatus, Ali spoke out about racism in America.

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NBA legend Kareem Abdul-Jabbar called Ali a friend and a mentor.

“At a time when blacks who spoke up about injustice were labeled uppity and often arrested under one pretext or another, Muhammad willingly sacrificed the best years of his career to stand tall and fight for what he believed was right,” Abdul-Jabbar wrote on Facebook.

Ali went on to win the heavyweight title twice more before retiring for good in 1981.

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CNN’s Ray Sanchez, Joe Sutton, Madison Park and Jason Hanna contributed to this report.