PHP RegEx Grouping Multiple Matches

I'm just trying my hand at crafting my very first regex. I want to be able to match a pseudo HTML element and extract useful information such as tag name, attributes etc.:

$string = '';

if (preg_match('/<(\w+?)(\s\w+?\s*=\s*".*?")+\s*>/', $string, $matches)) {
    print_r($matches);
}

Except, I'm getting:

Array ( [0] =>  [1] => testtag [2] => gamma="abc" ) 

Anyone know how I can get the other attributes? What am I missing?