A disgruntled former colleague killed a reporter and cameraman during a live broadcast in Virginia before shooting himself dead, say authorities.

Alison Parker, 24, and Adam Ward, 27, of CBS affiliate WDBJ, died at the scene of the attack during an interview in Smith Mountain Lake, Moneta.

The suspect, Vester Lee Flanagan, was pursued by authorities in a highway car chase before veering off the road in his rented Chevrolet Sonic and crashing.

The 41-year-old was later pronounced dead in hospital from a self-inflicted gunshot wound, state police said.

A recording of the broadcast at Bridgewater Plaza shopping centre showed the camera dropping to the ground as gunfire rang out.

The programme cut back to the studio where Kimberly McBroom, anchorwoman of the Mornin' newscast, was sitting in shock.

An image from the broadcast showed the gunman standing over the camera and pointing his weapon down.

Flanagan, who was fired by WDBJ in 2013 after workplace disputes, posted a horrifying video of the shooting to social media.

It showed the pistol being aimed at Ms Parker as she conducted her interview, oblivious to what is about to happen.

The footage showed the weapon blasting away at her before she turned and ran screaming.

Flanagan tweeted about filing an equal opportunities complaint and accused Ms Parker of having made racist comments.

WDBJ general manager Jeffrey A Marks said Flanagan, who used the on-air name Bryce Williams, was "an unhappy man".

He "quickly gathered a reputation as someone who was difficult to work with", said Mr Marks.

The station boss said they had fired him after "many incidents of his anger" and had to call police to escort him from the building.

ABC News reports it received a 23-page fax from Bryce Williams on Wednesday morning.

The author said he had been motivated to act by June's shooting of nine black churchgoers in South Carolina.

"The church shooting was the tipping point," the document said, "but my anger has been building steadily.

"I've been a human powder keg for a while…just waiting to go BOOM!!!!"

The fax said its author had been victimised for being black and gay.

Police said the suspect shot three people in the attack shortly before 6.43am on Wednesday.

The other victim was Vicki Gardner, of the Smith Mountain Lake Chamber of Commerce, who was being interviewed about local tourism.

She was shot in the back and is in a stable condition after surgery.

Mr Ward was engaged to Melissa Ott, a WDBJ news producer, who was working her last day on Wednesday before going to a new job in Charlotte, North Carolina.

He was planning to move with her.

Ms Parker was dating WDBJ anchor Chris Hurst and the couple had just moved in together.

"She was the most radiant woman I ever met," he tweeted.

The White House said it was another example of "all too common" gun violence in America and renewed calls for Congress to act.