A movie watching the state of explosion burning with fire shooting machine gun

There are about 2 minutes. Originally this video film was planned to be used within a certain program of NBC's overseas television station, but it seems that it came in as a result of Columbine high school gun shooting incident.

Below, that movie and reference material.
Knob Creek Machine Gun Night Shoot - Google Video

This is also the same kind of movie.

Dry Creek 2k3 - Google Video

There are also about 217 photos of this event in Flickr.

Knob Creek - 2003-2005 - a photoset on Flickr

What kind of machine gun is this?