public OnPlayerCommandText(playerid, cmdtext[])
{
    if(!strcmp(cmdtext,"/lock",true)) 
    {
        if(!IsPlayerInAnyVehicle(playerid)) return SendClientMessage(playerid,0xFFFFFFAA,"You have to be inside a vehicle.");
        for(new i=0; i < MAX_PLAYERS; i++)
        {
            if(i == playerid) continue;
            SetVehicleParamsForPlayer(GetPlayerVehicleID(playerid),i,0,1);
        }
        return 1;
    }
    return 0;
}