How do I parse an XML document that contains nodes where underscores exist?

<some_xml>
    <child_node>
        <child width_info="" height_info="" />
    </childnode>
</some_xml>

I tried this:

for each (var item:XML in Environment._XMLData.some_xml.child_node.child){
    trace(child.@width_info);
}

But that does'nt seem to work. I can't change the XML either because its from a third party. Any help would be great. Thanks in advance!