TSP roth account early withdrawl tax implication??

I have been out and separated from military service for about 1 year now, and during the time that I was in for 6 years, I have been contributing 3% to the Roth account and the Air Force matches the other 3%. I am looking into withdrawing the account and yes I am aware of the 10% early penalty fee for being under 59 and a half. However, is the remaining amount after the 10% penalty still taxed or not?

The agent over the TSP thrift line said that the only thing I'm being hit is the 10% early penalty fee, and the remaining would not be taxed since it's a Roth account and it has already been taxed. Is what she saying is true and correct? I just wanted a second opinion on this, thank you!