linear algebra - Determinant of $3 times 3$ block matrix

When I searched some properties of the determinant of block matrices, most results considered a $2 \times 2$ case. Let $A, B, C$ be $n \times n$ matrices and $I$ be an identity matrix of dimension $n$, and let $X$ be defined as follows

$$\begin{pmatrix}
A & 0 & 0 \\
B & I & 0 \\
C & D & I
\end{pmatrix}$$

Assume that $A$ is invertible. Then, what is $\det (X)$?