[robanswe]

new kills[MAX_PLAYERS];

public OnPlayerDeath(playerid, killerid, reason)
{
kills[killerid]++; // Adds one kill for killedid.
return 1;
}

if(strcmp(cmd, "/kills", true) == 0)
{
new str[256];

format(str, sizeof(str), "You have killed %d players )!",kills);//this is a example to haw to use this
SendClientMessage(playerid, 0xAA3333AA, str);
return 1;
}

This code besikly stores information of a playerid...