Retirement tax questions

I already withheld 30% from a early 401k withdrawal I made this year (I am under 59 and a half), and turbotax is also stating I owe another 10% for the penalty. But that has me paying a total of 40%, which if you take out the 10% early WD penalty puts me paying 30% income tax, but I am Not in the 30% tax bracket!  I am at a lower tax bracket.