LOS ANGELES: A Gospel choir singing "We're going to see the king" launched an emotional public memorial for Michael Jackson on Tuesday as the music world and thousands of fans bade farewell to the singer known as the "King of Pop."

Jackson's brothers carried the singer's gold-trimmed casket into the Staples Center sports arena in downtown Los Angeles for the memorial, the same place where Jackson rehearsed the day before his death for a highly-anticipated comeback tour.

Queen Latifah speaks during the memorial service for Michael Jackson at the Staples Center in Los Angeles, California, July 7, 2009.

Mariah Carey performed Jackson's 1970 hit "I'll Be There" and singer Smokey Robinson read out written tributes from former South African president Nelson Mandela and Diana Ross. Singer Stevie Wonder also sang and a glossy memorial program was filled with pictures of Jackson and testimonials from friends and family.

"Michael was the biggest star on earth," said actress Queen Latifah, to huge applause.

Michael Jackson's casket is carried into the Staples Center during his public memorial service in Los Angeles July 7, 2009.

Some 18,000 fans and friends got tickets in the arena or at a nearby, overflow theater for the ceremony, which took place against a large backdrop and picture of Jackson that read "In Loving Memory of Michael Jackson King of Pop 1958 - 2009."

Jackson's sudden death from cardiac arrest in Los Angeles on June 25 at the age of 50 prompted a worldwide outpouring of grief and sent sales of his biggest hits back to the top of the music charts.

Usher, Jennifer Hudson and Stevie Wonder were also expected to perform, while basketball star Kobe Bryant and civil rights leader Al Sharpton were among the other celebrity guests.

Jackson's family and close friends held a brief private ceremony earlier on Tuesday at a Los Angeles cemetery.

Dozens of fans watched from bridges as the funeral procession made its way along freeways cleared of traffic for one of the biggest celebrity events ever seen in a city accustomed to living with superstar citizens.

Police had estimated that more than 250,000 people would gather outside the arena to say farewell to the "Thriller" singer and one-time member of The Jackson 5.

But the orderly crowds were much smaller than expected and many fans and downtown office workers appeared to have stayed at home. The ceremony was carried live on most television networks.

Los Angeles resident Parisa Ebraihimi, 28, who said she has been a Jackson fan since she was five years old, came "to pay her final respects. "For me, his dance moves and his music -- all his songs were about a better world. He'll live on for generations," she said.

"This is certainly a momentous occasion that is probably as big, if not bigger than, when Elvis (Presley) passed away," said Steve Howard, a resident of Glendale, California, who won a ticket in an online lottery.

Tuesday's memorial focused on Jackson's musical achievements, overshadowed in the last 10 years by the darker side of the singer's life, including his humiliating 2005 trial and acquittal on charges of child sex abuse.

Questions persist over the cause of his death, which is being investigated by coroners, police and drug police amid reports of possible prescription medication abuse.

Police, security, escorts and sanitation for the memorial ceremony are expected to cost cash-strapped Los Angeles city council nearly $4 million. The city council on Tuesday launched a web site asking for fans to make donations towards the cost of hosting Tuesday's events.

The memorial was being shown live on U.S. television networks, in some 37 U.S. movie theaters, and was streamed on the Internet.

(L-R) Rebbie Jackson, Janet Jackson, Randy Jackson, Tito Jackson, Marlon Jackson, Jackie Jackson and Jermaine Jackson attend Michael Jackson's public memorial service held at Staples Center in Los Angeles July 7, 2009.

Members of the Jackson family act as pall-bearers during the memorial services for pop star Michael Jackson in Los Angeles July 7, 2009.

Musician Smokey Robinson speaks during the memorial service for Michael Jackson at the Staples Center in Los Angeles July 7, 2009. Michael Jackson's family and close friends held a private service at a Los Angeles cemetery on Tuesday as fans crowded into the city's downtown area for a star-packed public memorial to the "King of Pop."

Singer Jennifer Hudson performs, with the MJ Show Company dancers and the Andrae Crouch singers, at the Michael Jackson public memorial service held at Staples Center in Los Angeles July 7, 2009.

Usher performs next to Michael Jackson's casket during the memorial services for pop star Michael Jackson in Los Angeles July 7, 2009.

Queen Latifah eulogizes during the memorial service for Michael Jackson at the Staples Center in Los Angeles, California, July 7, 2009.

A fan sings along to the Michael Jackson song "Thriller" in Times Square while watching a live broadcast of memorial services for the late pop star, in New York July 7, 2009.

Fans react during the memorial service for Michael Jackson at the Staples Center in Los Angeles, California, July 7, 2009.

Fans watch a live broadcast of memorial services for Michael Jackson in Times Square, New York July 7, 2009.