If $h\_{1}, h\_{2}, \dots, h\_{N}$ are zero mean i.i.d Gaussian random variables with variance $\sigma\_{h}^{2}$, then how do I calculate the value of

$$\mathbb{E}\left[\left(h\_{1}^{2} + h\_{2}^{2} + \dots, h\_{N}^{2} \right)^{2}\right]$$

The only clue I have is that

$$\mathbb{E}\left[h\_{i}^{2}\right] = \sigma\_{h}^{2}$$

I do not know how to compute $\mathbb{E}\left[h\_{i}^{2} h\_{j}^{2}\right]$ (for all $i \neq j$). Please help.