PHP - XML SOAP Extracting Data

I hope I am posting this in the right place.

I am working with a response, that is captured in a PHP variable (response from a cURL post). That response looks something like this.

<soapenv:Envelope xmlns:log="" xmlns:soapenv="" xmlns:xs="" xmlns:xsd="">

<wssb:Security xmlns:wssb="" xmlns:wsu="">
<wsu:Timestamp wsu:Id="WS9ae008c3-a845-13a8-a6a0-dd227c7c567e">
<wssb:UsernameToken wsu:Id="abcd-efg-hijk">
<wssb:Password Type="wssb:PasswordDigest">1234ABCD=</wssb:Password>

What I need to do is capture the element “wssb:Security”. In other words, extract all of the information between: “<wssb:Security” and “</wssb:Security>”.

What would be my best approach in doing so?
I am new to this, so a code example would be greatly appreciated along with any references.