Reporter Alison Parker, 24, and cameraman Adam Ward, 27, were killed by Vester Lee Flanagan live on-air during an interview on the WDBJ7 TV station in Moneta, Virginia.
Flanagan, who goes by the name Bryce Williams, later shot himself after posting first-person footage of his attack on social media.
He was taken to nearby Nova Fairfax Hospital to be treated for "life-threatening injuries", Virginia state police confirmed, before dying at around 1.30pm local time.
Around 11.30am local time (4.30pm GMT) state police reported that they had spotted his vehicle and tried to pull him over, but he sped away.
His car then "ran off the road and crashed".
When officers approached the car they "found the male driver suffering from a gunshot wound". After this he was transported to hospital.
Flanagan was a disgruntled co-worker who was at the station for about a year.
He filmed the shocking murder on his phone and tweeted it from an account he set up last week, which has now been suspended.
Speaking at a press conference, Sheriff Bill Overton confirmed Flanagan's death and said they were starting "a long investigation, because there are a lot of components".
He added that the gunman "was disturbed and at some point in his life he started spiralling out of control".
A number of other tweets have emerged from his account, in which he accuses Parker of making "racist comments".
He wrote: "Alison made racist comments. EEOC report filed.
"They hired her after that???
"Adam went to HR on me after working with me one time!!!"
National news station ABC News said they received a 23-page fax from someone claiming to be Flanagan.
They said: "Sometime between Tuesday night and this morning, ABC News received a fax from someone claiming to be Bryce Williams.
"It is a lengthy document: 23 pages. ABC News has turned it over to authorities."
In shocking live footage of the incident, Miss Parker can be seen speaking to a guest.
The camera then begins to shake and shots are heard being fired.
A woman can be heard screaming as the camera falls to the ground.
Mr Ward managed to capture images of Flanagan after he fell to the floor.
The footage then quickly cuts to the news anchor in the studio.
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