Fans have begun to gather outside the Staples Center in Los Angeles for Michael Jackson's memorial concert, amid strong police presence. The show, which begins at 1000 LA time (1800 BST), will feature Mariah Carey, Lionel Richie and Stevie Wonder. Concrete barriers have been erected outside the concert hall, where Jackson had been rehearsing a comeback show before his untimely death on 25 June. The memorial will be broadcast in the UK on BBC Two and Sky Arts 1. Other people due to take part in the service include Motown boss Berry Gordy, Lionel Richie, Jennifer Hudson, and Britain's Got Talent finalist Shaheen Jafargholi, who has played the young Michael Jackson in the musical Thriller - Live. More than 1.6 million people applied for one of the 11,000 passes issued for the event, with an additional 6,500 issued for a screening at the nearby Nokia Theatre. A total of 8,750 people were chosen at random to receive a pair of tickets to attend the ceremony. But many ticketless fans have arrived in Los Angeles hoping to get into the Staples Center, including Briton Vikkie Spencer. "We just wanted to come and there's going to be loads of people around anyway and we're just going to be part of it," she said. "We're just going to go and wait outside and hope to buy some [tickets]". The Los Angeles Police Department, trying to avoid a mob scene, have warned those without tickets they will not be able to get close to the venue. Assistant police chief for Los Angeles, Jim McDonnell, told CNN he did not anticipate any trouble. "It will be a crowd that gathers for the right reasons and keeps the reason they're there in mind," he said. One person who will not be attending is Jackson's former wife and the mother of two of his children, Debbie Rowe. "The onslaught of media attention has made it clear her attendance would be an unnecessary distraction to an event that should focus exclusively on Michael's legacy," her lawyer Marta Almli said in a statement. "Debbie will continue to celebrate Michael's memory privately." Jackson's long-time friend Elizabeth Taylor has also declined the opportunity to speak at the memorial. "I cannot be part of the public whoopla [sic]," she wrote on Twitter. "And I cannot guarantee that I would be coherent to say a word." "I just don't believe that Michael would want me to share my grief with millions of others. How I feel is between us. Not a public event."