Alison Parker was interviewing a woman at about 6:45 a.m. when shots rang out. Both women screamed.
As the camera fell to the ground, the audience caught the briefest glimpse of a man who appeared to point a gun toward the downed cameraman.
The station cut away to a shocked anchor, Kimberly McBroom, back in the studio.
Parker, 24, and photographer Adam Ward, 27, were killed in the shooting at Bridgewater Plaza near Moneta, the station, WDBJ-TV, reported later.
Ward's fiancée was in the control room and saw the shooting, WDBJ General Manager Jeff Marks told CNN.
The woman being interviewed, Vicki Gardner, executive director of the Smith Mountain Lake Regional Chamber of Commerce, was shot in the back and is in surgery, said Barb Nocera, the chamber's special projects manager said.
The gunman is believed to have fired six or seven times, Marks said.