Unfortunately, the entire distribution is taxable and, subject to additional 10% penalry if it is also an early withdrawal.
There are a few, very specific exceptions (I'm inlcuding a link that lists them) to an early withdrawal. Turbo Tax will ask you if you qualify for any of them, after the Form 1099-R is entered in Turbo Tax. If you don't qualify for them, the entire amount is taxable and subject to an additional penalty, unfortunately.
https://www.irs.gov/Retirement-Plans/Plan-Participant,-Employee/Retirement-Topics-Tax-on-Early-Distr...
