Multiple touch at a time

hey,
I am working on a two player game for android devices.Like a game which you can play with your friend on the same phone.
But the problem is the gui buttons of the two players are not working at the same time. Like if i am moving my spaceship the other player can’t move his spaceship. I am using function onmousedown. Please help
Here’s the script-

#pragma strict
var player1 : Rigidbody2D;

function Start () {

}

function Update () {

}
function OnMouseDown()
{
player1.transform.Translate(5,  0, Time.deltaTime);

}

If you need to track multiple touches, you can’t use the mouse functions. The mouse functions only work if there is one touch at a time.

Instead, you’ll need to get familiar with some of the other things in the Input class.

You can also find some stuff in the Asset Store that might simplify things.