ROANOKE, Va. — He was a fired television reporter with a history of conflicts at work and rage apparently stoked by racial grievances. And when he sought revenge on Wednesday, gunning down two former colleagues, he used the tools of social media to ensure that his crime was broadcast live, recorded from multiple angles and posted online.

Vester Lee Flanagan II, 41, identified by the authorities as the gunman, waited until Alison Parker and Adam Ward, young journalists at WDBJ in Roanoke, were on air, then killed them while recording on his own video camera. Mr. Flanagan shot himself in the head hours later, the authorities said, but as the chase for him was on, he wrote about the shooting on Twitter, uploaded his video to Facebook and sent a manifesto to ABC News that spoke admiringly of mass killers and said that as a black, gay man he had faced discrimination and sexual harassment.

The shooting and the horrifying images it produced marked a new chapter in the intersection of video, violence and social media.

The day began with the most mundane of early-morning interviews. Ms. Parker and Mr. Ward were working on a story for WDBJ about the 50th anniversary of Smith Mountain Lake, a reservoir tucked among farms and rolling mountains that is popular with anglers, kayakers and sunbathers. They stood on a balcony of Bridgewater Plaza, a shopping and office complex on the lakeshore, talking with Vicki Gardner, executive director of the Smith Mountain Lake Regional Chamber of Commerce.