How to catch anything between //BEGIN and //END blocks?

How to catch anything between //BEGIN and //END blocks?

//BEGIN domain
//data for domain
'domain'=>array(
'site'=>'4',
'domain'=>'test.dev',
'locale'=>'en_US',
'site'=>'2',
'domain'=>'anothertest.dev',
'locale'=>'de_DE',
'site'=>'3',
'domain'=>'localhost',
'locale'=>'nl_NL',
),
//END domain
How can I catch anything between the //BEGIN and //END blocks. And
preg_replace it. I tried using '///BEGIN (.*) //END/'. But the new lines
are troublesome.