UPDATE: TMZ now reports the actor suffered a heart attack in his home. According to quote to Daily News from a Los Angeles Fire Department spokewoman, "At 10:40 this morning we received a call for a medical emergency. An adult male patient was transported to St. John's hospital. It was a 911 call."

Actor Garry Shandling, best known for his work as a stand-up comedian and time on numerous series including The Larry Sanders Show, died at St. John's Health Center in Santa Monica Thursday, TMZ reports.

His death appears sudden and cause of death is unknown. A source close to Shandling said he'd been fine and speaking to people Thursday morning, but at some point, someone made a 911 call from his house. The name of the hospital where he was sent was not available at press time, but he arrived at the facility alive.He was not suffering from any known illness at the time of his death.

Shandling had a storied career that featured numerous awards wins, including two British Comedy Awards, eleven CableACE Awards and a BAFTA Award. He also often served as a regular fill-in for Johnny Carson on The Tonight Show, and wrote on the series Sandford and Son and Welcome Back, Kotter before debuting in his own series, It's Garry Shandling's Show, which was inventive for having its characters break the fourth wall and openly acknowledge they were on a TV show. The actor has also various film appearance in features such as Iron Man 2, Captain America: The Winter Soldier, Zoolander and Dr. Dolittle.