Michael Jackson fans in the city and around the world continued Friday to mourned the loss of the music icon, who died suddenly the previous day at age 50.

After conducting a three-hour autopsy Friday, the Los Angeles coroner's office said there was no foul play in the death of the performer, who got his start at the Apollo Theater in the 1960s. The exact cause of death, however, will take weeks to be determined.

"The cause of death has been deferred. What that means is that the medical examiner has ordered additional testing such as toxicology and other studies," said Craig Harvey of the Los Angeles coroner's office. "Those tests, we anticipate, will be completed over the next four to six weeks."

The spokesman gave few details, but said that the superstar had been taking some unspecified prescription medications and showed no external trauma.

"The Los Angeles Police Department has requested that a security hold be placed on the investigation of Mr. Jackson, so there's an extremely limited amount of information that we will be able to discuss about the case," said Harvey.

The body was released to Jackson's family on Friday and has since been taken to an undisclosed location. Funeral plans have not yet been announced.

The LAPD said the BMW of Jackson's personal physician, who was on hand when Jackson was stricken, was impounded because it may contain medications or other evidence that could assist the coroner. A spokesperson stressed that the doctor is not under criminal investigation.

Jackson was rushed to UCLA Medical Center from his Los Angeles home after suffering cardiac arrest Thursday afternoon, hospital officials said.

According to a 911 call made from Jackson's home during the incident, the singer was not breathing or responsive to treatment from his personal doctor.

Brian Oxman, a family friend and former lawyer for Jackson, said he was concerned about Jackson's use of painkillers. Oxman claimed Jackson had been taking prescription drugs to help with pain suffered when he broke his leg after a fall off a stage.

"He had over-medicated and it was a serious problem and the exact people who were doing this, I'm not going to point any fingers, but I warned this was a problem," said Oxman. "This is my worst fear; it is a nightmare."

Fans have been gathering outside the Apollo Theater in Harlem since hearing news of his death. The Jackson 5 performed at the famed theater in the late 1960s before Jackson became an international pop icon in the 1980s.

Cardboard boxes were laid out at the entrance to the theater so mourners could leave messages and flowers.

"I'm looking at the videos, looking at the news; all I did was cry," said one fan. "So I just need to be around people that are celebrating his life. I love Michael Jackson."

"It really breaks my heart because he was a very special man and we're going to miss him," said another. "I know that he's in heaven with James Brown and all the greats before him. There will never be another Michael."

"By far, one of the most talented people on the planet Earth," said a third. "I'm just so sorry to see him go."

"He was an inspiration to everybody, old and young," said a fourth fan. "We love you, Michael, that's all I can say."

"I knew all of his dance moves and everything," said a young fan. "I'm just sad that he passed."

The Apollo will hold two special tributes to honor Jackson next week.

The first is scheduled for 2 p.m. Tuesday, where 600 people at a time can go in and see video tributes and listen to his music. The Reverend Al Sharpton and the president of the theater will give eulogies. Fans will also have the opportunity to leave flowers and messages for the late pop star.

On Wednesday, the theater will dedicate Amateur Night to the King of Pop and is expected to feature a variety of special performances. Audience members will also be encouraged to moonwalk and dance like Jackson.

Mayor Michael Bloomberg said at an unrelated event earlier Friday that Jackson left an indelible mark on the city.

"He was idolized by many New Yorkers, both young and old, and like everyone, everywhere we’re just stunned and saddened by his death," said the mayor. "I think it’s fair to say he really was a one-of-a-kind music talent. And I just want his family and loved ones to know that New Yorkers are thinking of them and that the King of Pop will always be remembered here in the entertainment capital of the world – and I will always be listening to his music. "

The Reverend Jesse Jackson, a close family friend, said he met with the singer's family in Los Angeles Friday.

"We talked about a lot of old times... a lot of great memories, and that really is Michael's legacy as a cultural-changing musical icon," said the reverend.

In Hollywood, fans also stood in line to lay flowers and pay homage at Jackson's star at the Hollywood Walk of Fame.

The world watched Jackson grow up as a member of the Jackson 5. He stayed popular as a solo artist, with his album "Off the Wall" going platinum in 1979.

His 1982 album "Thriller" remains one of the best-selling album of all time with hits like "Billie Jean" and "Beat It" as well as the title track. He introduced the world to the moonwalk, and his signature sequined glove.

Jackson's career suffered major setbacks amid charges of child molestation. In 2005, Jackson was cleared of charges he molested a 13-year-old boy at his Neverland Ranch.

Radio stations across the nation, including in New York, were spinning Jackson's records in tribute.

"I know we had a lot of other things that have preoccupied the situation around his name," said Kiss FM music producer James Mtume. "But the most important thing is, here's a cat, 50 years old, who laid down enough music that we'll study it for another 200 years."

"Instant party classics, instant party bangers," said Hot 97 radio DJ Cipha Sounds. "It doesn't matter what type of event you're at. It could be an underground hip hop event or a super pop movie premiere, Michael Jackson always works. Always."

Stores and online retailers attempted Friday to keep up with fans' demands for Michael Jackson CDs, DVDs and books.

Amazon.com officials said they sold out of all CDs by Michael Jackson and the Jackson 5 just hours after the singer's death was announced.

Fans also flocking to iTunes. Just before Jackson's death, only one of his songs ranked on the site's top 100 songs, but by Friday afternoon, eight of the top 10 albums were Michael Jackson's.

Jackson was currently preparing for a comeback tour in London that was to start next month.

He is survived by his three children.