How do I convert a c# two-dimensional array to a JSON object?

If I have a two-dimensional array in C# - how can I convert it into a JSON string that contains a two dimensional array?

eg.

int[,] numbers = new int[8,4];
JavaScriptSerializer js = new JavaScriptSerializer();
string json = js.Serialize(numbers);

gives a flat one-dimensional array in a JSON object. The Microsoft documentation states:

'A multidimensional array is serialized as a one-dimensional array, and you should use it as a flat array.'