Describe the irreducible components of the projective variety

$\displaystyle X=${$\displaystyle [x_0,x_1,x_2,x_3]:x_0x_1-x_2x_3=x_0x_2-x_1x_3=0$}$\displaystyle \subset \mathbb{P}^3(k)$.

(Hint:You may find it easier to work first in the distinguished affine neighborhoods.)