*

Marines detain man for nearly two hours, hand him over to

DHS

*

Some 1,8000 anti-Trump demonstrations planned for Saturday

*

LA County sheriff says fewer than 1% of demonstrators

causing

harm

(Adds mayor's press conference)

By Omar Younis, Brad Brooks, Phil Stewart and Idrees Ali

LOS ANGELES, June 13 (Reuters) - U.S. Marines deployed

to Los Angeles made their first detention of a civilian on

Friday, part of a rare use of military force to support domestic

police and coming ahead of national protests over President

Donald Trump's military parade in Washington.

The detention of a the man, a U.S. Army veteran and an

immigrant who obtained U.S. citizenship, punctuated a series of

highly unusual events that have appealed to Trump supporters but

outraged other Americans who are demonstrating discontent in the

streets.

Trump ordered the Marines to Los Angeles in response to

street protests over immigration raids, joining National Guard

forces already deployed to the city over the objection of

California's governor. Trump said troops were necessary to quell

the protests - a contention that state and local officials

dispute.

About 1,800 protests are scheduled across the U.S. on

Saturday in opposition to the Washington military parade that

marks the 250th anniversary of the U.S. Army and coincides with

Trump's 79th birthday.

Both the military parade and domestic use of active duty

troops are uncommon for the United States, as was the military

detention of a U.S. citizen on American soil. It was also

unusual when federal agents forcibly removed and

handcuffed a U.S. Senator

on Thursday as he interrupted a press conference by

Homeland Security Secretary Kristi Noem.

Trump has thrived politically on unconventional tactics.

But Democratic opponents are starting to push back.

Fifteen protests are expected in Los Angeles alone, Mayor Karen

Bass said, urging people to remain peaceful.

"We are here today because the raids have caused fear

and panic," Bass said, joined by two dozen elected officials to

oppose the raids and military presence. "Can the federal

government come in and seize power from a state and from a local

jurisdiction? How much will the American people put up with?"

About 200 Marines were assigned to protect the Wilshire

Federal Building in Los Angeles, part of a battalion of 700

Marines sent to support the National Guard, said Army Major

General Scott Sherman, who is in command of both the National

Guard and Marine forces.

The Marines and National Guard deployed in Los Angeles are

assigned to protect federal property and personnel and may

temporarily detain people, but they are required to turn them

over to civilian law enforcement for any formal arrest.

ARMY VETERAN DETAINED

Reuters witnessed Marines detain one person at the Wilshire

Federal Building. Reuters images showed Marines restraining his

hands with zip ties and then handing him over to civilians from

the Department of Homeland Security (DHS) nearly two hours

later.

U.S. military confirmed the detention after being presented

with Reuters images, in the first known detention by active duty

troops.

The detained man, Marcos Leao, 27, an immigrant and a U.S.

Army veteran, said after he was released that he was told to get

on the ground upon venturing into a restricted area, as he

crossed a line of yellow tape to avoid walking around the

building.

Leao, who said he is Portuguese and Angolan and became a

U.S. citizen through the military, said he complied with all

commands and that the Marines apparently mistook him for a

protester when he simply had business with the Veterans

Administration office inside the building.

"They treated me very fairly," Leao said, adding that he was

told, "Understand, this is a whole stressful situation for

everybody, and we all have a job."

Asked about the incident, the U.S. military's Northern

Command spokesperson said active duty forces "may temporarily

detain an individual in specific circumstances," and that the

detention would end when the person is transferred to civilian

law enforcement.

DHS referred press queries to the Northern Command.

Meanwhile, Los Angeles demonstrations continued for an

eighth straight day, after they were sparked last Friday by a

series of immigrations raids.

The demonstrations have been concentrated in the downtown

area, and fewer than 1% of those present have caused problems,

Los Angeles County Sheriff Robert Luna said.

Some people have been charged with assaulting a police

officer, looting, or damaging property.

There was a "big difference" between legitimate protesters

and "people who are coming out to cause problems," Luna said at

a press conference in which law enforcement officers said they

welcomed peaceful protests on Saturday but warned they would

arrest those who harm others or damage property.

Bass implemented a curfew over one square mile (2.5 square

km) of the downtown area, which officials said has been useful

for maintaining order.

Bass said there was "no termination date" for the

curfew.

"We are hoping that if the cause of the turmoil ends,

which is stopping the raids, then I can almost guarantee you the

curfew will go away in short order," Bass said.