How do I grab SOAP XML attributes on the server side?

I have been pulling my hair out all day today and yesterday on this. I am trying to grab the “errorString” attribute in the “meterRead” node that the client sends me if there is a problem. Here is an example of the XML body.

<ns1:changedMeterReads><ns1:meterRead objectID="11" errorString="Error reading Meter Number 39002708, Description: Response for this meter read was not found.">
<ns1:meterNo xsi:type="xsd:string">39002708</ns1:meterNo></ns1:meterRead>

On the server side to grab the “meterNo” node I would simply reference it by doing $changedMeterReads->meterRead->meterNo, but how would I get the “errorString” attribute? I’ve searched the internet far and wide and have not found anything.