Gary Shandling Dead at 66

Comedian Garry Shandling died at an L.A. area hospital on Thursday of a Massive Heart Attack.

The 66-year-old star was not suffering from any illness ... as far as we know .... A source connected to Shandling says he was healthy and speaking to people on Thursday morning.

Our source says there was a 911 call from "The Larry Sanders Show" star's home, and he was transported to the hospital. We're told Shandling was alive when he arrived at the hospital: Source