Accessing sub elements of 'loader'

I have the following XML in a ‘loader’ through Ajax call:

<Room Category>
        <Price Gross='44.00' Nights='5' />
        <PriceInfo>Some price info</PriceInfo>
        <Price Gross='40.00' Nights='10' />

Note that there can be an unknown number of PriceRange nodes.

I also have the following code:

priceranges = loader.doXml('//RoomCategory/PriceRanges/PriceRange')

I want to iterate over each PriceRange and get the Gross Attribute for each Price node. Note that the Price node within the PriceRange is sometimes at childNode[1] and sometime at childNode[2] depending on whether the PriceInfo node exists. I have tried the following but that does not work.

for(pr=0; pr<priceranges.length; pr++)
  price = priceranges[pr].childNode['Price'].getAttribute('Gross')

However that does not work. Firebug says:

priceranges[pr].childNode.Price is undefined.

Please can you tell me how to get to the Price node from priceranges[pr].