"Unfortunately it is true," said spokeswoman Jill Fritzo.A Beverly Hills police officer told reporters at a briefing that emergency assistance received a call from the Beverly Hilton at around 3:20 p.m. PST, and the singer was pronounced dead at 3:55 p.m."She has been positively identified by friends and family that were with her at the hotel, and next of kin have already been notified," Lieutenant Mark Rosen told reporters.No other details were immediately available.Houston was in Los Angeles for the Grammy Awards, the music industry's biggest honors program that will take place on Sunday night. She died hours before she was expected to perform at record producer Clive Davis's annual pre-Grammy party on Saturday, which is held at the Beverly HiltonHouston, inspired by soul singers in her New Jersey family, including mother Cissy Houston and cousins Dionne Warwick and the late Dee Dee Warwick, as well as her godmother Aretha Franklin, became one of the most celebrated female singers of all time, taking multiple Emmy, Grammy and Billboard Music awards.Her popularity soared in the 1980s and 1990s with consecutive No. 1 hits including the smash single "I Will Always Love You," from the soundtrack of the feature film "The Bodyguard," in which she starred.Immediately, reactions came pouring in from fans and friends in the music industry."I am absolutely heartbroken at the news of Whitney's passing," legendary music producer Quincy Jones said in a statement. "... I always regretted not having had the opportunity to work with her. She was a true original and a talent beyond compare. I will miss her terribly."Pop star Rihanna posted on Twitter "No words, just tears," and rapper Nicki Minaj tweeted "Jesus Christ, not Whitney Houston. Greatest of all time."