Protected Pages in MediaWiki

I am currently using MediaWiki as a documentation website, with login authenticated by LDAP. However, we have hit a snag. Certain pages contain sensitive information. For example links that say "click here to log in". I would like to be able to protect certain pages from being edited by just anyone. I would like to allow certain groups of users (like employees) to edit those pages. How do I set up page protection by group in MediaWiki (if it is possible)?