PHP Array to JSON Array using json encode

Question

I have encoded an Array I've made using the inbuilt json_encode(); function. I need it in the format of an Array of Arrays like so:

[["Afghanistan",32,12],["Albania",32,12]]

 It is returning as:

{"2":["Afghanistan",32,12],"4":["Albania",32,12]}

How can I remove these row numbers without using any Regex trickery?