TIBURON, Calif. -- Comedic actor Robin Williams died at his Northern California home Monday, law enforcement officials said. Williams was 63.
Coroner investigators suspect "the death to be a suicide due to asphyxia," according to a statement from the Marin County, California, Sheriff's office.
"Robin Williams passed away this morning," his media representative Mara Buxbaum said.
"He has been battling severe depression of late. This is a tragic and sudden loss. The family respectfully asks for their privacy as they grieve during this very difficult time."
Williams married graphic designer Susan Schneider in Napa Valley, California, ceremony in October 2011. Schneider sent a written statement through the representative.
"This morning, I lost my husband and my best friend, while the world lost one of its most beloved artists and beautiful human beings. I am utterly heartbroken.
"On behalf of Robin's family, we are asking for privacy during our time of profound grief. As he is remembered, it is our hope the focus will not be on Robin's death, but on the countless moments of joy and laughter he gave to millions."
Marin County deputies responded to an emergency call from Williams' home in unincorporated Tiburon, California, at 11:55 a.m., reporting "a male adult had been located unconscious and not breathing," the release from the sheriff said.
Williams was pronounced dead at 12:02 p.m., it said.
Word of Williams' death stunned the entertainment community and beyond Monday.
President Barack Obama's statement sent from the White House summed it up:
"Robin Williams was an airman, a doctor, a genie, a nanny, a president, a professor, a bangarang Peter Pan, and everything in between. But he was one of a kind. He arrived in our lives as an alien -- but he ended up touching every element of the human spirit. He made us laugh. He made us cry. He gave his immeasurable talent freely and generously to those who needed it most -- from our troops stationed abroad to the marginalized on our own streets."
Comedian Steve Martin tweeted, "I could not be more stunned by the loss of Robin Williams, mensch, great talent, acting partner, genuine soul."
Former CNN host Larry King said he would he remember Williams as "a genuine caring guy. Not just a funny man, but a guy who cared about people."
Williams was last seen alive at his home, where he lives with his wife, at about 10 a.m., the sheriff's statement said.
"An investigation into the cause, manner and circumstances of the death is currently underway by the Investigations and Coroner Divisions of the Sheriff's Office," the sheriff's statement said.
An autopsy is scheduled for Tuesday, the sheriff said.
Williams made at least two trips to rehab for drug treatment, including a visit this summer, and he underwent heart surgery in 2009.
Williams, born in Chicago on July 21, 1951, studied theater at Juilliard School before taking his stand up act to nightclubs. He was cast as Mork, an alien visitor to Earth, for a 1974 episode of television's "Happy Days."
"Happy Days" star Henry Winkler said it was "unimaginable that this is the reality today, that this incredible human being, incredible, delicate, funny, dramatic human being is gone."
Winkler said he "realized I was in the presence of greatness" at Williams' first rehearsal as Mork.
"I just realized my only job is to keep a straight face," said Winkler, who played "The Fonz." "And it was impossible. Because no matter what you said to him, no matter what line you gave to him, he took it in, processed it, and then it flew out of his mouth, never the same way twice. And it was incredibly funny every time."
The role led to the spin-off show "Mork & Mindy," which showcased Williams' usual comic improvisation talents. It was set in Boulder. In one episode, Williams appeared as a member of the Pony Express, which was the Denver Broncos' cheerleading team at the time.
"He arrived in our lives as an alien - but he ended up touching every element of the human spirit," President Barack Obama said about Robin Williams.
Williams proved his dramatic acting skills in "Good Will Hunting," a 1997 film that earned him a best supporting actor Oscar.
Williams credited the influence of Jonathan Winters' comic irreverence and quirky characters as a great influence on his comedy. The connection between the two was completed when Winters was cast as Williams' son on "Mork & Mindy."
When Winters died in 2013, Williams said he was "my idol, then he was my mentor and amazing friend." He tweeted that Winters was his "Comedy Buddha."
"Mork & Mindy" co-star Pam Dawber simply said "I am completely and totally devastated. What more can be said?"
WIlliams and Dawber reunited on TV earlier this year on an episode of the CBS comedy "The Crazy Ones."
Williams' fans can look forward to four more movie appearances coming to theaters, including another installment in the "Night at the Museum" franchise.
The film, set for a December release, has Williams reprising the Teddy Roosevelt role he delivered in the first two comedies.
No matter what problems someone is dealing with, the National Suicide Prevention Lifeline is ready to help 24 hours a day, seven days a week. 1-800-273-TALK.
CNN contributed to this report.