Etta James Funeral: Christina Aguilera, Stevie Wonder Perform (Video)

Christina Aguilera and Stevie Wonder were among those paying tribute to singer Etta James at a private funeral held Saturday.

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Held at the Greater Bethany Community Church City of Refuge, friends and family remembered the late singer, with Rev. Al Sharpton reading a personal note written by President Barack Obama.

In it, the president declared that James, who died at 73 on Jan. 20 in Riverside, Calif., "transcended genres" and that the "At Last" singer would be most "remembered for her voice," CNN reports.

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"I know she will be sorely missed by all those who knew and loved her," Sharpton read from Obama's letter.

A tearful and emotional Aguilera sang James' "At Last" (watch the performance below) while Wonder performed "Shelter in the Rain" and "The Lord's Prayer."

During Sharpton's eulogy, he noted James' modest upbringing in Southern California, observing that she began as a girl singing gospel in church.

"I think it was her authenticity that was part of the charisma that drew people to her ... It was Etta James that bridged rhythm and blues with rock and roll," Sharpton said.

Though Saturday's funeral, which began at 10 a.m., was for friends and family, hundreds of fans waited to attend the public viewing at Inglewood Cemetery Mortuary.

Since James' death, Billboard reports that sales have spiked 378 percent.

Late last year, reports surfaced that the Grammy Award winner and Rock and Roll Hall of Famer was terminally ill after her live-in doctor two weeks earlier declared her leukemia incurable.

James was diagnosed in 2009 with Alzheimer’s disease, was hospitalized in 2010 because of a dangerous staph infection and hospitalized again in May with a blood infection. Other health problems were self-inflicted: James had a decade-long addiction to heroin that frequently put her in psychiatric hospitals for weeks at a time.

The singer, whose other hits include “All I Could Do Is Cry,” “Sunday Kind of Love,” “Pushover,” “Tell Mama” and a version of The singer, whose other hits include “All I Could Do Is Cry,” “Sunday Kind of Love,” “Pushover,” “Tell Mama” and a version of Muddy Waters’ “I Just Want to Make Love to You,” moved among blues, R&B, gospel, jazz and rock ’n’ roll during her six-decade career.