Washington DC - The FBI said Thursday it was launching a full-scale terror probe after a gunman carried out what officials described as an "ambush-style" attack near the White House, shooting two National Guard soldiers multiple times with a revolver.

The young soldiers shot Wednesday remained in critical condition, as America was jolted on what is normally a quiet day with family and friends on the Thanksgiving holiday.

The shooter was identified as 29-year-old Afghan national Rahmanullah Lakanwal, who worked with US forces in his country during the war against the Taliban and settled in America after the Islamists seized power again in 2021 and the Americans withdrew chaotically.

The shooter faces charges of assault with intent to kill, and if the guardsmen die, he will face first-degree murder charges, US Attorney for the District of Columbia Jean Pirro told a news conference.

Crime New details emerge about main suspect in shooting of National Guard members near White House

"You picked the wrong target, the wrong city, and the wrong country," Pirro said.

"It is an ongoing investigation of terrorism," FBI director Kash Patel told the same news conference.

He said officials are investigating any associates the suspect had either back home or in the US.

"That is what a broad-based international terrorism investigation looks like," Patel said.

Officials said Lakanwal, armed with a .357 Smith and Wesson revolver, staged an ambush attack on the two National Guard members.

The soldiers were deployed to Washington under President Donald Trump's much-disputed use of military forces in Democrat-run cities to fight what he calls rampant violent crime.

Pirro said the shooter walked up to the soldiers near a subway stop a stone's throw from the White House and started shooting "without provocation, ambush style."

"One guardsman is struck, goes down, and then the shooter leans over and strikes the guardsman again," Pirro said. "Fellow guardsmen who were there responded, immediately, engaging the suspect, neutralizing the threat and subduing him at the scene."