Cross thread access problem in ResponseCallback in Windows Phone 7

Basically, I'm getting some data from a WebService, and in the ResponseCallback I'm trying to fill an ObservableCollection with the results I got from the response, but I get an `UnauthorizedAccessException` "Invalid cross-thread access" when I try to do so. What would be the best way to fill said observable collection when I get the result? Thanks! This is the code: ``` public ObservableCollection<Person> People { get; set; } private void ResponseCallback(IAsyncResult asyncResult) { HttpWebRequest request = (HttpWebRequest)asyncResult.AsyncState; HttpWebResponse response = (HttpWebResponse)request.EndGetResponse(asyncResult); string responseString = string.Empty; using (Stream content = response.GetResponseStream()) { if (request != null && response != null) { if (response.StatusCode == HttpStatusCode.OK) { XDocument document = XDocument.Load(content); var people = from p in document.Descendants() where p.Name.LocalName == "PersonInfo" select Person.GetPersonFromXElement(p); foreach (Person person in people) { this.People.Add(person); // this line throws the exception } } } content.Close(); } } ```