Talk show host Conan O'Brien broke the news of actor Robin Williams' death during Monday afternoon's taping of his late night talk show on TBS.

After announcing the untimely death of Williams, which was apparently a result of suicide, O'Brien, Andy Richter and guest Will Arnett paid tribute to the late actor, according to Boston.

"This is absolutely shocking and horrifying and so upsetting on every level," O"Brien said.

Richter added, "He was an amazingly kind and generous person, and it's got to be a terrible time for his family and our thoughts go out to them."

Guest star Arnett quipped, "As funny as he was - he's truly one of the all-time greats - he was even better as a person. He was just one of the loveliest, sweetest, kindest guys that I've ever worked with."

O'Brien closed the tribute with only the kindest words for the "Mrs. Doubtfire" actor, People Magazine reported.

"We're just processing this information literally at this moment. We are thinking of Robin's family, we're thinking about everyone how he touched around the world throughout his life, and we're thinking about Robin tonight."

He continued, "We're so very sorry to have to report this to anybody who's hearing it for the first time. We are going to end our show now. I'd like to thank all of my guests. Good night, and God bless Robin Williams."

Meanwhile, other A-list celebrities mourned the death of the actor via Instagram. "Keeping Up with the Kardashians" stars Khloe and Kim posted an image of Genie from "Aladdin," which Williams voiced in the 90s.

The siblings wrote, "Genie, you're free! #RIP #RobinWilliams #Sad."

"American Idol" judge Jennifer Lopez posted a photo of herself with the late actor and wrote via Instagram, "Sad, sad, day... My condolences to Robin's family & friends. He brought light to every room he entered & was a true comedic genius. The world will miss you, Robin! #RIPRW."