Insert List into database in ASP.Net MVC

There are 270 items in a list.i want insert all in one go.how can i do this?

 [WebMethod]
    public string get_ScaData()
    {
        var json = string.Empty;
        string XmlResult = string.Empty;
        string serviceUrl = "http://www.eass.upsldc.org/eass/webservice?service=scadadata&passcode=82570fd5701811e8beb3dc4a3eea412d";
        using (System.Net.WebClient wc = new System.Net.WebClient())
        {
            if (IsValidUrl(serviceUrl))
            {
                json = wc.DownloadString(serviceUrl);
                var user = Newtonsoft.Json.JsonConvert.DeserializeObject<System.Collections.Generic.List<scadaData>>(json);

            }
            else
            {

            }
        }
        return XmlResult;
    }