YouTube user NickyFlips was exiting the building for a jury summons at the time of the shooting and took video capturing the sound of gunfire. While the video doesn't show the events, rapid-fire gunshots can be heard while the citizen videographer says, "I think they got him," toward the end of the clip.
Authorities have yet to uncover a motive for the shooting, but Barbara Morgan, a Las Vegas police spokeswoman, told the Associated Press, "It looks like he went in there and just started unloading, we don't know."
Update: The Los Angeles Times reports, "A deputy U.S. marshal is wounded and a court security officer dies, along with the gunman, identified as Johnny Lee Wicks, a 66-year-old retiree disgruntled over cuts in his Social Security benefits."