Hollywood is reacting with pure shock and horror to the terrible news of legend Rob Reiner's death. On Sunday, it was confirmed that Rob and his wife of 36 years Michele Singer Reiner were killed in their own home - allegedly by their son Nick. Their 28-year-old daughter Romy was apparently the one to find them in their Brentwood, California home with their throats slit and called the Los Angeles Fire Department. LAPD Captain Mike Bland told AP that the Robbery Homicide Division is investigating an "apparent homicide," as a source informed Perez Hilton that Nick, their 32-year-old son who has faced addiction issues in the past, was in custody. TMZ reported Nick has officially been arrested and is being held on a $4 million bail. So incredibly awful. Rob has spanned an impressive Hollywood career both in front of and behind the camera, famously directing films like The Princess Bride, Misery, and A Few Good Men, and many, many more. And now some of Hollywood's finest is reacting to the news. Related: Chiefs ELIMINATED From Playoff Contention As Patrick Mahomes Suffers Brutal Injury! Across social media, celebs expressed horror, disbelief, and pure shock in reaction to the blood-curdling news: Ben Stiller: "What a huge loss. Rob Reiner was one of my favorite directors. He made some of the most formative movies for my generation. He came out from behind a huge comedic shadow of the great Carl Reiner and being a TV actor to being a a great director who made an incredible run of movies. Spinal Tap is one of the best comedies ever made - and the list goes on. He was a kind caring person who was really really funny. I didn't know him well but was always a fan and I feel a real sadness for those who did, and his family." John Cusack: "Shocked by the death of Rob Reiner - a great man." Paul Feig: "Rob was my true hero. A true visionary titan and a lovely lovely person. One never knows if it's proper to post during something as tragic as this. But I just want the world to know what so many of us know in the industry. Rob was the best." Barack Obama: "Michelle and I are heartbroken by the tragic passing of Rob Reiner and his beloved wife, Michele. Rob's achievements in film and television gave us some of our most cherished stories on screen. But beneath all of the stories he produced was a deep belief in the goodness of people - and a lifelong commitment to putting that belief into action. Together, he and his wife lived lives defined by purpose. They will be remembered for the values they championed and the countless people they inspired. We send our deepest condolences to all who loved them." Gavin Newsom: "Jen and I are heartbroken by the tragic loss of Rob Reiner and Michele Singer Reiner. Rob was the big-hearted genius behind so many of the classic stories we love, with projects as wide-ranging as The Princess Bride to A Few Good Men. His boundless empathy made his stories timeless, teaching generations how to see goodness and righteousness in others - and encouraging us to dream bigger. That empathy extended well beyond his films. Rob was a passionate advocate for children and for civil rights - from taking on Big Tobacco, fighting for marriage equality, to serving as a powerful voice in early education. He made California a better place through his good works. Rob will be remembered for his remarkable filmography and for his extraordinary contribution to humanity." Nancy Pelosi: "The news of a deadly assault on Rob and Michelle Reiner in their home is devastating. It's hard to think of anyone more remarkable and excellent in every field and endeavor they pursued. Rob was creative, funny, and beloved. And in all of their endeavors, Michelle was his indispensable partner, intellectual resource, and loving wife. Personally, Rob cared deeply about people and demonstrated that in his civic activities - whether by supporting the First 5 initiative or fighting against Prop 8 in California. Civically, he was a champion for the First Amendment and the creative rights of artists. And professionally, he was an iconic figure in film who made us laugh, cry and think with the movies he created. Paul and I and our entire family mourn the loss of our very dear friends and are praying for their loved ones during an unimaginable time of grief." Stephen King: "I'm horrified and saddened by the death of Rob Reiner and Michele. Wonderful friend, political ally, and brilliant filmmaker (including 2 of mine). Rest in peace, Rob. You always stood by me." Roseanne: "I'm absolutely shocked and horrified to hear about Rob Reiner and his wife Michele. This is a travesty. Praying for swift justice. Sympathies to their family and children. I'm at a loss for words" Ron Howard: "#RIPRobReiner Our careers and lives intersected often over the decades from Rob writing the pilot script for Happy Days and then as we each shifted from acting careers into directing and producing. He proved to be a superlative filmmaker, a supportive colleague and at