Iterate an array 4 by 4

Hi guys, i'm trying to create an iteration on a array that need to count 4 by 4. I explain better:

 var users = new Array();
     var selectDataMessage : String;
     selectDataMessage= "selectDataMessage";
         
     selectDatasMessage = URL + "?selectDataMessage="+selectDataMessage;
     var dataMessage: WWW = new WWW(selectDatasMessage); 
     yield dataMessage;
     
     users = dataMessage.text.Split(";"[0]); // this is an array

i get from php a string with all users that left a message on my game, so for example, in users, at position [0][1][2][3] i've all the information i need for a single player (name surname, gender, username)

the problem is the iteration i did something like this:

     for(var i : int = 0; i < users.length;i++){
             //Debug.Log("User length "+users.length);
             firstNames.Push(users[i]);
             lastNames.Push(users[++i]);
             userNames.Push(users[++i]);
             gender.Push(users[++i]);
     }

this one get every single position and it put them inside 4 arrays each for every single data i need.

I know it's not really good but it's the only way i found . It doesn't work anyway, it goes off by one. and return this error:

 ArgumentOutOfRangeException: Index is less than 0 or more than or equal to the list count.
 Parameter name: index
 1

someone know how to solve this? thanks a lot.