The Army initiated an administrative investigation, called a 15-6, after a UH-72 Lakota was seen making low maneuvers in Washington, D.C., on Monday, Army Secretary Ryan McCarthy said. The crew was grounded immediately after the investigation began, he added.
"It's an administrative automatic when you initiate a 15-6," McCarthy said. "It's procedure."
The defense secretary and head of the National Guard in D.C. both ordered an investigation into the matter. McCarthy said he expects it to wrap up soon.
"I'm going to get an interim update later today," he said.
The incident is one of several apparent shows of force that have come under scrutiny this week amid national protests after George Floyd, a black man, died in police custody in Minneapolis. McCarthy said he has not had any direct reports of Army or Air National Guardsmen activated in Washington being violent against peaceful protesters.
Videos showed Lakota and UH-60 Black Hawk helicopters kicking up debris as officials tried to force demonstrators who'd broken the city's 7 p.m. curfew off the streets. The Black Hawks were reportedly operated by the FBI.
McCarthy declined to say who ordered the helicopter crews to fly low over the protesters in Washington, citing concerns that he's in the chain of command and the investigation remains ongoing.
"We're going to try to get it closed … as quickly as possible," he said.
Maj. Gen. William Walker, the head of the D.C. National Guard, said when announcing the investigation that he wants to ensure all involved complied with safety regulations and procedures.
"I hold all members of the District of Columbia National Guard to the highest of standards," he said in a statement. "We live and work in the District, and we are dedicated to the service of our nation."