Like most of us, Hollywood was shocked and saddened by the death of pop icon Whitney Houston at age 48. Celebrities took to Twitter in droves to express their sadness and condolences.

Mariah Carey, who sang with the duet "When You Believe" with Whitney, changed her Twitter photo to a shot of them together smiling.

Mariah Carey @MariahCarey: Heartbroken and in tears over the shocking death of my friend, the incomparable Ms. Whitney Houston.... My heartfelt condolences to Whitney's family and to all her millions of fans throughout the world.... She will never be forgotten as one of the greatest voices to ever grace the earth.

Others echoed Mariah's praise for Whitney as one of the "greatest voices" and quoted one from her arguably her most famous song "I Will Always Love You."

iamdiddy @iamdiddy: Whitney Houston!!! OMG!! I really can't believe this.. This is one of the saddest days ever..

Gloria Estefan @GloriaEstefan: Someone please tell me that it's not true about Whitney Houston passing! Such an amazing talent!

Randy Jackson @YO_RANDYJACKSON: wow I am devastated. the world has lost another one of the best voices in history. RIP whitney houston...

La Toya Jackson @latoyajackson: I can't fathom the fact that #whitneyhouston has died! My heart goes out 2 her mother, daughter & her love ones. #Whitney U will be missed!

Katy Perry @katyperry: So devastating. We will always love you Whitney, R.I.P.

Justin Bieber @justinbieber: just heard the news. so crazy. One of the GREATEST VOICES EVER just passed. RIP Whitney Houston. My prayers go out to her friends and family

demetria lovato demetria lovato @ddlovato: I Look To You - Whitney Houston.... :'(

Nina Dobrev @ninadobrev: #iwillalwaysloveyou is one of the most beautiful and iconic songs. It will be remembered forever. Rest in peace Whitney Houston

Ralph Macchio @ralphmacchio: Wow, just heard - been off the grid the last few hours. So sad. RIP Whitney. THE Voice!

Billy Ray Cyrus @billyraycyrus: R. I. P. Whitney Houston. I will always love you and your music and talents will live on forever.

LA LA @lala: Words can not express my sadness and sorrow at this time. Praying for Whitney Houston and her family. Somethings are truly unbelievable.... I love you Whitney Houston. There will never be another. Ill always remember the sound of your voice and the impact ur music had on my life

Rev Run @RevRunWisdom: My heart is saddened.. Everyone please keep Whitney Houstons family in their prayers.. May she rest in peace

DJ Pauly D @DJPaulyD: R.I.P Whitney Houston So Sad

Amber Patrice Riley @MsAmberPRiley: I had to pull over off the road. RIP Whitney Houston. I'm glad now that I got to meet you and thank you for your beautiful music.

Jenna Ushkowitz @JennaUshkowitz: RIP Whitney Houston #Iwillalwaysloveyou

Kevin McHale @druidDUDE: it's incredible the impact one voice can have. Whitney, you changed so much. A true Icon.

Damian McGinty @damianmcginty: Speechless. An icon, an incredible singer...lost for words. RIP Whitney Houston. Life is a scary thing.

Hoda Kotb @hodakotb: So shocked and saddened to hear abt Whitney Houston #RIP Whitney

soleil moon frye @moonfrye: RIP Whitney. The world will always and forever love you....

Melissa Joan Hart @MellyJHart: I'm shocked to hear about Whitney Houston!!! RIP!! You will be missed!

Eliza Dushku @elizadushku: Oh #WhitneyHouston no.. We will always love you. #RIPWhitney

Sean Hayes @theseanhayes: The voice of a music legend has been quieted today. R.I.P. for one of the most amazing artists of our time - Whitney Houston.

Selita Ebanks @MsSelitaEbanks: #Moment of silence for one of the greatest voices of all time.... Whitney Houston :-( #RIP

Keshia K Pulliam @peachespulliam: I just read that Whitney Houston died today... I am in shock!! We've lost too many amazingly talented people this year

Patton Oswalt @pattonoswalt: We watched this happen in super-slow motion. Horrible. #RIPWhitney

Nicki Minaj @NICKIMINAJ: Jesus Christ, not Whitney Houston. Greatest of all time.

SHAQ @SHAQ: R .i.p to a Newark legend Whitney houston. I'm gonna miss auntie ,this one hurts. We lost a legend dam dam dam. Thank you for everything

Lea Michele @msleamichele: I'm speechless. Such sad news about Whitney Houston..

Ricki Lake @RickiLake: Listening to #WhitneyHouston on the radio. What a loss. :(

AKON @Akon: We've lost another Legend. RIP WHITNEY HOUSTON. I'm Honored to have had the chance to work with such an amazing human Being

Mena Suvari @mena13suvari: OMG!!! RIP Whitney Houston! You forever were and always will be amazing. A voice that brought inspiration to many.

Goldie Hawn Goldie Hawn @goldiehawn: I am so very sad to hear of Whitney Houston's passing. She was one of our great artist that graced us all. May she rest in peace.

Jay Manuel @MrJayManuel: The American Golden Voice has been silenced. RIP Whitney Houston. Her rendition of the Star Spangled Banner always moved me to tears.

Naya Rivera Naya Rivera @NayaRivera: Oh my gosh. I'm speechless. R.I.P. Whitney Houston.

John Legend @johnlegend: I hope the Grammys can put together a tribute at the last minute

Beth Behrs @BethBehrs: Whitney Houston gone. Wow. In shock. Grew up listening to her.

NeNe Leakes @NeNeLeakes: OMG Noooooooo! I was just @ an event Thursday & Whitney was there! I can't right now

Sherri Shepherd @SherriEShepherd: Praying for Whitney Houston's family. Especially her daughter Bobbi Kristina

LeAnn Rimes Cibrian @leannrimes: Whitney Houston was the first cd I ever bought. She had a God given gift. Hopefully, she's singing with angels now.

Taraji P. Henson Taraji P. Henson @TherealTaraji: LORD HAVE MERCY!!!! We've lost another great! RIP Whitney Houston! My heart hurts.

Paris Jacksoη Paris Jacksoη @ParisJackson:R.I.P. Whitney Huston, I've always idolized her and her amazing talent <3

boygeorge @BoyGeorge: Whitney is dead, OMG, I'm so heartbroken. You were amazing and I hope you have found peace! x

Rob Lowe @RobLowe: Whitney Houston gone. Voice of a lifetime. So sad.

Lance Bass @LanceBass: Another incredible talent lost way too soon. Thanks for entertaining us all Whitney!

Piers Morgan @piersmorgan: Stunned by Whitney Houston's death at just 48 - one of the greatest voices ever heard. #RIP

Kendall Jenner @KendallJenner: Wow. RIP Whitney Houston. #sosad #somuchtalent

Nia Vardalos @NiaVardalos: RIP Whitney Houston, we sang along and fell in love to your songs.

Pete Wentz - RE:PETE @petewentz: RIP whitney

Kirstie Alley @kirstiealley: Oh my...heartbreaking.. to the Family and friends of Whitney Houston, deepest regards ...

Holly Robinson Peete @hollyrpeete: Whitney: Thank You. You gave so much to us. Inspired the world. #soundtrackofmylife #iwillalwaysloveyou

Brandi Glanville @BrandiGlanville: OMG just saw that Whitney Houston died! RIP! I'm crying :(

Denise Richards @DENISE_RICHARDS: So sad to hear about Whitney Houston..my heart goes out to her loved ones and her daughter..

Chloë Grace Moretz @ChloeGMoretz: Omg..whitney houston died..we've lost another amazing singer

Danica Patrick @DanicaPatrick: Can't believe Whitney Houston passed away. So sad. "I will always love you" will live forever. She made beautiful music.

Trevor Donovan @trevdon: Whitney Houston left a magnificent musical legacy & thats how she should be remembered. She made millions of people happy with her songs

Shaun Robinson @MsShaunRobinson: I'm in shock. Whitney Houston's publicist just confirmed that I had the last SOLO sit-down interview with Whitney.