By Omar Younis, Brad Brooks, Phil Stewart and Idrees Ali LOS ANGELES (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.

After a day of peaceful protests in Los Angeles, tensions mounted between protesters and Marines outside the federal building in downtown LA.

"No one signs up to join the United States Marine Corps to attack protesters," U.S. Rep. Seth Moulton, D-6th District, a former Marine, told MSNBC on Sunday.

All traffic has been halted on a portion of the 101 freeway in Los Angeles as protesters walk on the freeway, according to Los Angeles Police Department. Both northbound and southbound lanes have been impacted, officials said. "101 freeway between Alameda and the 110 freeway is closed due to demonstrators walking onto the freeway," police said.

More than 700 Marines based out of the Marine Corps Air Ground Combat Center in California have been mobilized to respond to the protests in Los Angeles, and the troops will join the thousands of National Guard members who were activated by President Donald Trump over the weekend without the consent of California’s governor or LA’s mayor.

The Pentagon is scrambling to establish rules to guide U.S. Marines who could be faced with the rare and difficult prospect of using force against citizens on American soil, now that the Trump administration is deploying active duty troops to the immigration raid protests in Los Angeles.

U.S. Attorney Bill Essayli said at least nine people face federal charges related to the demonstrations. The protests have been prompted by Immigration and Customs Enforcement sweeps spurred by President Trump's directive to find immigrants living in the United States without legal status.