Task.WhenAll never ends

Hi guys! Could someone explain please why same piece of code works fine in Windows Console application but hangs forever in Android? Here is the code:

            protected override void OnCreate (Bundle bundle)
            {
                        var _client = new HttpClient();
                        var taskList = new List<Task<string>>();

                        for (var i = 0; i < 10; i++)
                        {
                            taskList.Add(GetString(_client));
                        }

                        var responces = Task.WhenAll(taskList).Result;
            }
            private static async Task<string> GetString(HttpClient _client)
            {
                     var responce = await _client.GetAsync("http://www.123greetings.com/");
                     return responce.Content.ReadAsStringAsync().Result;
            }