SimpleXMLElement Add Child Closure

I'm trying to create a simple XML document but I'm having difficulty grouping the children appropriately. My XML should look like this:

<news><abc><content>test</content></abc><content2>test2</content2></abc></news>

I'm using the following code:

$newsXML = new SimpleXMLElement("<news></news>");
$news = $newsXML->addChild('abc');
$news->addChild('content','test');
$news->addChild('content2','test2');
echo $newsXML->asXML();

and getting this:

<news><abc><content>test</content><content2>test2</content2></abc></news>

How do I separate the children?