I would like to know if there are in the literature explicit computations of the volume of complex hyperbolic manifolds. 

More precisely, let $\mathcal O$ be an imaginary quadratic number field, and let $\Gamma$ be the set of "integer" elements in $U(n,1)$, that is
$$
\Gamma = U(n,1) \cap M(n+1,\mathcal O).
$$

How much is the volume of the complex hyperbolic manifold $M\_\Gamma = H\_{\mathbb C}^n / \Gamma$?

The answer for $\mathcal O=\mathbb Z[\sqrt{-1}]$ is enough for me.

It's known that 
$$
\mathrm{vol}(M\_\Gamma) = \frac{(-\pi)^n 2^{2n}}{(n+1)!}\; \chi(M\_\Gamma),
$$
where $\chi(M\_\Gamma)$ denotes the Euler characteristic of $M\_\Gamma$, but I couldn't find computed the term $\chi(M\_\Gamma)$ in the literature.

Thank you in advance.-.