How do I filter an 2D array based on a value in a column?

I tried arr[arr[2] > 5] but it fails

>>> arr = np.arange(12).reshape((4,3))
>>> print(arr)
[[ 0  1  2]
[ 3  4  5]
[ 6  7  8]
[ 9 10 11]]
>>> print(arr[arr[2] > 5])
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
IndexError: boolean index did not match indexed array along dimension 0; dimension is 4 but corresponding boolean dimension is 3