Washington DC - President Donald Trump on Thursday said that one of the two members of the National Guard who were shot a day earlier near the White House has died.

"She was savagely attacked, she's dead," Trump said of 20-year-old Sarah Beckstrom, who served in the West Virginia National Guard.

The president added that the other trooper who was shot, 24-year-old Andrew Wolfe, was fighting for his life.

On Wednesday afternoon, the two victims were on patrol near Washington's Farragut West metro station, not far from the White House, when a gunman opened fire.

Executive Assistant Chief of the Metropolitan Police Department Jeffery Carroll said that Rahmanullah Lakanwal, the only suspect in the shooting, had been subdued by other members of the National Guard, arrested, and transported to hospital for treatment.

Jeanine Pirro, US attorney for the District of Columbia, on Thursday said the 29-year-old Afghan national, lived in Bellingham in Washington state, with his wife and five children. He reportedly drove across the country to the capital before the attack.

He used a revolver in the attack and faces 15 years for assault with the intent to kill while armed, Pirro said. She made it clear that this was a preliminary assessment. The motive for the attack was initially unclear.

Reporting has revealed Lakanwal's long ties to the US Army and the CIA, with whom he worked for years before joining the 2021 evacuation as the Taliban retook control of the country.