C＃Regex - 在2个相同的单词及其子行之间进行多次匹配

I have text like this:

我有这样的文字:

 INIT -- FOO
   UP: 1
     UpLine #1
   DOWN: 2
     DownLine #1
     DownLine #2

  INIT -- BAR
   UP: 0
   DOWN: 2
     DownLine #1
     DownLine #2
 INIT -- FO