Minimal normal subgroups are elementary Abelian

Hey, can anybody help me with this?

If $\displaystyle G$ is a finite group with a minimal non-trivial normal subgroup $\displaystyle M$ such that $\displaystyle M$ is Abelian, then $\displaystyle \exists p \in \mathbb{N}^+$ prime such that $\displaystyle \forall x \in M \backslash \{e\}, o(x) = p$.

I have no idea where to start with this. I can see that all proper non-trivial subgroups of $\displaystyle M$ aren't normal in $\displaystyle G$, but not sure how this helps.