By Brad Brooks, Phil Stewart, Idrees Ali and Dietrich Knauth LOS ANGELES (Reuters) -Hundreds of U.S. Marines arrived in the Los Angeles area on Tuesday under orders from President Donald Trump, as the city's mayor declared a curfew for parts of the downtown area and police arrested 197 people in a fifth day of street protests.

A cloud of uncertainty is hanging over Los Angeles, where questions remain over the role that Marines and National Guard troops will play after being called in by President Donald Trump amid protests over immigration raids in the city.

Six Americans tell the BBC that there's clearly a problem in Los Angeles - they just don't agree with who's at fault.

The Marines and the National Guard personnel deployed amid the protests in to Los Angeles will operate under the same rules of force and will not be engaging crowds unless necessary, according to two U.S. officials.

President Donald Trump did not invoke the Insurrection Act in a June 7 memo that deployed the California National Guard to Los Angeles. He cited a federal law that says if the U.S. faces a rebellion, the president may call into federal service the state National Guard.

Massachusetts senators Elizabeth Warren and Ed Markey called Trump's move to deploy the National Guard to quell LA protests "authoritarian."

Protests over immigration raids in the Los Angeles area are set to continue for a third day. Gov. Gavin Newsom said President Trump’s decision to call in National Guards was “purposefully inflammatory.

The California Governor has sued the U.S. President over the mobilization of the National Guard, calling it “an unmistakable step toward authoritarianism.”

Unlike the 1992 riots, protests have mainly been peaceful and been confined to a roughly five-block stretch of downtown LA, a tiny patch in the sprawling city of nearly 4 million people. No one has died. There’s been vandalism and some cars set on fire but no homes or buildings have burned.