updated 05/19/2011 AT 5:30 PM ET
•originally published 05/20/2011 AT 12:45 PM ET
After a long history of health problems and addiction, Taxi star Jeff Conaway fell into a coma a week ago in Los Angeles.
The latest crisis for the troubled actor, 60, came as a surprise to those closest to him.
“He seemed fine early last week,” his manager of eight years, Phil Brock, told PEOPLE on Thursday. “He had spoken with his agent and his management team and even attended an autograph signing. He really seemed in fine spirits.”