Great.
Here's the difference between the UK and US.
In the UK the shooter didn't have a gun so didn't shoot anyone. Therefore the armed civilian didn't have a gun and couldn't stop the shooter not shooting anyone.
In the US the shooter had a gun and killed at least 26 people but the armed civilian had a gun and could come along and stop it.
The right wing in the US will therefore see this as guns being positive because guns stopped the whole thing, whereas without guns the armed civilian couldn't stop the shooter from killing people, even though he wasn't killing anyone because he didn't have a gun.
What a twisted place America is.