grammatical number - What is the proper plural of the word "freshman"?

Would it be proper to say freshman students, freshmen, or freshmen students?

Edit:

It is worth noting that I have since learned it is more acceptable in educational circles to use the term "first-year students" instead of "freshmen".

Answer

Both "freshmen" and "freshman students" are correct, but "freshmen students" is wrong. I think "freshmen" is the official term.