Hello, how can I match the text between the words START and END usig FLEX regular expressions ?

Example:

this is line 1
START text beetwen two commands END
this is line 3
START
this is line 5
this is line 6
END
this line 8

Thank you.

I've never used Flex-regex, but this one works in a lot of the regex engines I've worked with:

(?s)START(?:(?!END).)*END

Thanks for the answer, I only know LEX style for regex, I understand your logic, how can I translate that to LEX format ? someone knows ?