Zip encoded stream dilemma.

[stardv]

I have a case where I tried everything and I am stuck on finding right solution. I will appreciate any suggestions.
Here is a scenario. I am sending XML request to the server and receive response as a stream what is a zip file.
I am trying to get the CSV file that is zipped. How do I get to data?
I ma just confused what format it comes in a stream. The stream that comes back has type: Net.ConnectStream

Here is the code for retrieving response:
HttpWebResponse response = (HttpWebResponse) request.GetResponse();
responseStream = response.GetResponseStream();

When response is in ASCHI encoding I can easily read it using StreamReader
However when it comes in zip format , I am confused how to retrieve data.

Thank you a lot.