Singer Michael Jackson, who rose to fame performing with his brothers as a child and became an international superstar whose personal life was constant fodder for the tabloid media, died Thursday after collapsing at a rented estate in Bel Air.

The “King of Pop,’’ whose musical achievements were overshadowed later in life by his often-eccentric behavior and accusations of lewd behavior with young boys, was in Los Angeles preparing for a series of 50 London concerts that he said would be his final on-stage performances.

Paramedics responded to the gated mansion in the 100 block of Carolwood Drive at 12:21 p.m., according to Los Angeles Fire Department spokesman Devin Gales. The 50-year-old Jackson, who was not breathing and was unresponsive when paramedics arrived, was taken to Ronald Reagan UCLA Medical Center, where he was pronounced dead.

Jackson’s brother, Jermaine, told reporters at the hospital that his brother, “the legendary King of Pop,’’ died at 2:26 p.m.

“It is believed he suffered cardiac arrest in his home, however, the cause of his death is unknown until the results of the autopsy are known,’’ he said. “His personal physician, who was with him at the time, attempted to resuscitate my brother, as did the paramedics who transported him to Ronald Reagan UCLA Medical Center.

“Upon arriving at the hospital at approximately 1:14 p.m., a team of doctors including emergency physicians and cardiologists attempted to resuscitate him for a period of more than one hour and they were unsuccessful. Our family requests that the media please respect our privacy during this tough time. And we all loved being with you, Michael, always.’’

Craig Harvey of the Los Angeles County coroner’s office said an autopsy could be performed as early as Friday, but the exact cause of death may not be determined for six to eight weeks, depending on what type of tests are ordered.

Detectives from the Los Angeles Police Department’s Robbery/Homicide division were sent to the Bel Air home to investigate the scene. Lt. Gregg Strenk told reporters at the home that it is routine for police to investigate any death, but the elite Robbery/Homicide detail was sent solely based on the high-profile nature of Jackson’s death.

News of Jackson’s death brought a throng of local, national and international media and fans to hospital grounds on the UCLA campus searching for more information. Media crews gathered outside the Jackson family’s compound in Encino, and more fans made their way to the Hollywood Walk of Fame.

Michael Jackson’s Walk of Fame star was blocked because of a movie premiere at Grauman’s Chinese Theatre, but some fans visited the star of The Jacksons at 1500 Vine St. Other fans held a vigil on the star of radio announcer and talk show host Michael Jackson, despite knowing that it wasn’t the singer’s star.

Members of the Jackson family, including his mother, Katherine, gathered inside the hospital. His father, Joseph, was on his way back to the Southland from Las Vegas. Jackson’s brothers, sisters and friends and relatives comforted each other as the singer’s music was played, longtime family attorney Brian Oxman said.

“They are simply hugging one another,’’ Oxman told KCAL9. “This is just one of the saddest occasions. The music of Michael Jackson has been echoing off the walls here at UCLA. It has been one of the most surreal experiences of my life. I’ve never seen anything like it and the fans here who are so extraordinary. They loved this man. I loved this man. He was my friend.’’

Jackson, who became known as the “King of Pop’’ with the success of albums such as “Thriller,’’ “Bad’’ and “Dangerous,’’ first gained national exposure with his brothers — Tito, Jermaine, Jackie and Marlon — as part of the Jackson 5. The group opened for artists such as Gladys Knight and the Pips and James Brown.

Motown founder Berry Gordy signed the group in 1968. But as their popularity grew, some of the Jackson brothers began branching out on their own.

Some brothers continued performing as The Jacksons, but it was Michael who became a sensation — most notably with the 1979 release of the album “Off the Wall.’’ His status as a musical superstar was cemented in 1982 after the release of “Thriller,’’ an album that generated seven top-10 hits and still ranks as the top-selling album of all time.

While performing his hit song “Billie Jean’’ on a television special celebrating the history of Motown, Jackson showed off what would become one of his signature dance moves — the moonwalk, a move he said he developed after watching French mime Marcel Marceau.

Further raising Jackson’s iconic status was the video for “Thriller.’’ The roughly 15-minute video, directed by John Landis, remains one of the most popular music videos of all time and continues to be emulated.

“I am absolutely devastated at this tragic and unexpected news,’’ said music producer Quincy Jones, who worked with Jackson on multiple albums. “For Michael to be taken away from us so suddenly at such a young age, I just don’t have the words. Divinity brought our souls together on ‘The Wiz’ and allowed us to do what we were able to throughout the 80s.

“To this day, the music we created together on ‘Off the Wall,’ ‘Thriller’ and `Bad’ is played in every corner of the world and the reason for that is because he had it all — talent, grace, professionalism and dedication. He was the consummate entertainer and his contributions and legacy will be felt upon the world forever. I’ve lost my little brother today, and part of my soul has gone with him.’’

As he grew older, Jackson became known for his flamboyant clothes, trademark sunglasses and sequined glove he wore on one hand, earning him the nickname “The Gloved One.’’ His brothers largely faded from the public eye, but his sister, Janet, built a wildly successful music career of her own.

Over the course of his career, however, Michael Jackson’s personal life came under more and more scrutiny, most notably an obvious change in his skin tone. In 1993, Jackson told Oprah Winfrey that the change was caused by a skin disease. He was also rarely seen in public without a surgical mask over his face.

Also during that time, a 13-year-old boy claimed that Jackson had fondled him during a sleepover at the singer’s 2,900-acre Neverland Ranch compound in Los Olivos in Santa Barbara County. Jackson denied any wrongdoing and eventually reached a financial settlement with the boy’s family.

In 2005, Jackson was tried and acquitted of lewd conduct with a minor in Santa Barbara County. After the trial, Jackson moved to Bahrain, far from the constant media scrutiny that dogged him in California.

Beset by financial difficulties, Jackson sold Neverland Ranch in 2008.

He married Lisa Marie Presley in 1994, but they divorced after only two years. He then married a nurse named Debbie Rowe, who — through artificial insemination — became the mother of two of his children, Michael Joseph Jackson Jr. and Paris Michael Katherine Jackson. He had another son, Prince “Blanket’’ Michael Jackson II, with an unknown woman.

Jackson and Rowe divorced in 1999.

Jackson was in the midst of preparing for a series of 50 concerts in London’s O2 Arena. Tickets for the shows rapidly sold out, and a limited number of extra tickets were put on sale on Wednesday. But rumors about the singer’s health had been raising questions about whether Jackson would actually perform all 50 shows.

Neil Portnow, president and CEO of the National Academy of Recording Arts and Sciences, praised the 13-time Grammy winner.

“Rarely has the world received a gift with the magnitude of artistry, talent and vision as Michael Jackson,’’ Portnow said. “He was a true musical icon whose identifiable voice, innovative dance moves, stunning musical versatility and sheer star power carried him from childhood to worldwide acclaim. A 13-time Grammy recipient, Michael’s career transcends musical and cultural genres and his contributions will always keep him in our hearts and memories. We are deeply saddened by this tragic news and our hearts go out to his family and to music lovers around the globe who mourn this great loss.’’

Gov. Arnold Schwarzenegger said “the world has lost one of the most influential and iconic figures in the music industry.’’

“From his performances with the Jackson 5 to the premiere of the ‘moonwalk’ and ‘Thriller,’ Michael was a pop phenomenon who never stopped pushing the envelope of creativity,’’ Schwarzenegger said. “Though there were serious questions about his personal life, Michael was undoubtedly a great entertainer and his popularity spanned generations and the globe. Maria and I join all Californians in expressing our shock and sadness over his death and our hearts go out to the Jackson family, Michael’s children and to his fans worldwide.’’