From the New York Times, I'm Michael Barbaro. This is The Daily.

Today, 12 of the weapons found in the gunman's hotel in Las Vegas

were reportedly modified with a simple device that can be bought online

but effectively transforms a legal firearm into an automatic weapon.

What is a bump-stock and where did it come from?

It's Thursday, October 5th.

So, Chris, the morning after the shooting, you're hearing the audio of what happened in Las Vegas

and what are you hearing?

Well, what I heard was what everyone heard was this long, extended burst of fire

that sounded like an automatic weapon.

Sounds like a machine gun. Chris Chivers is an investigative reporter at the Times.

And the reason I was thinking that initially was the length of the burst.

I mean, it was impossible to count the rounds, but it was far more than the traditional magazines

you would hear in a sole rifle.

You would almost never hear this long, sustained, continuous burst that we heard out of that hotel

and that essentially sounded like it continued until the shooter was out of ammunition.

And it didn't make immediate sense to me that someone who had military training

would shoot like this because that's not the way infantry veterans are trained to fire.

They fire in short bursts and they fire six or eight rounds

and they'll be a pause, they'll re-aim and reorient the weapon, they'll fire in other six or eight rounds.

So when I heard it, my initial impression was this person doesn't come from a military background.

And how is it you know that?

...