1:52 PM PT -- In the 911 call -- obtained by TMZ -- a male caller tells emergency operators Reynolds is experiencing trouble breathing and chest pain. The caller also says Reynolds is awake but not answering questions. The call was made just after noon on Thursday.
12:54 PM PT -- Burt was cast in Quentin Tarantino's Charles Manson film, "Once Upon a Time in Hollywood," but a source connected to the project tells us Burt hadn't shot his scenes yet.
He was supposed to shoot for 2 days, playing George Spahn .