WDBJ journalist Alison Parker, 24, and cameraman Adam Ward, 27, were shot at close range while conducting an on-air interview. The gunman was still at large.
"We do not know the motive. We do not know who the suspect or the killer is," said WDBJ general manager Jeffrey Marks as he confirmed the deaths to viewers.
WDBJ is located in the southern Virginia city of Roanoke.
Marks said Parker and Ward were "both in love with other members of the team" at WDBJ.
The woman that Parker was interviewing on a balcony at the lakeside Bridgewater Resort in the town of Moneta, near Roanoke, was reportedly wounded.
Parker was talking to the woman about tourism development for WDBJ's early-morning newscast when the gunman seemingly closed in from behind.
Several shots were heard, as well as screams, as Ward's camera fell to the floor, capturing a fuzzy image of the gunman, dressed in dark clothing.
The station then cut away to a startled anchorwoman back in the studio.
A screengrab image of Parker before she was shot while conducting an interview. - AFP Photo/WDBJ7/Handout
On her Facebook page, Parker -- whose birthday was just a week ago -- described herself as the "mornin' reporter" at WDBJ with an interest in ballroom dancing.
WDBJ anchor Chris Hurst tweeted that he and Parker were "very much in love," adding: "I am numb."
"She worked with Adam every day. They were a team. I am heartbroken for his fiancee," Hurst said.
Virginia Governor Terry McAuliffe said on Twitter that he was "heartbroken over (the) senseless murders."
Virginia state police were working with local authorities to capture the gunman, he said.
In other development, the shooting suspect has been identified as Vester Lee Flanagan, also known on-air as Bryce Williams.
According to international news reports, police said Flanagan had attempted suicide and is in critical condition.
This TV video frame grab courtesy of WHSV TV, in Harrisburg, Virginia shows shooting suspect Vester Lee Flanagan, also known as Bryce Williams. - AFP Photo /WDBJ7-TVMeanwhile, social media was abuzz over the incident:
Virginia Governor Terry McAuliffe also tweeted his message of condolence.
Netizens also expressed their shock over the incident which happened during a Live broadcast:
Meanwhile, some netizens in the United States expressed their concerns over the country's gun controls.
