Misleading photographs, videos and text have spread widely on social media as protests against immigrant raids have unfolded in Los Angeles, rehashing old conspiracy theories and expressing support for President Trump’s actions.

The flood of falsehoods online appeared intended to stoke outrage toward immigrants and political leaders, principally Democrats.

They also added to the confusion over what exactly was happening on the streets, which was portrayed in digital and social media through starkly divergent ideological lenses. Many posts created the false impression that the entire city was engulfed in violence, when the clashes were limited to only a small part.

There were numerous scenes of protesters throwing rocks or other objects at law enforcement officers and setting cars ablaze, including a number of self-driving Waymo taxis. At the same time, false images spread to revive old conspiracies that the protests were a planned provocation, not a spontaneous response to the immigration raids.

The confrontation escalated on Monday as new protests occurred and Defense Secretary Pete Hegseth announced — on X — that he was mobilizing 700 Marines from a base near Los Angeles to guard federal buildings. They are expected to join 2,000 members of the California National Guard whom Mr. Trump ordered deployed without the authorization of the state’s governor, Gavin Newsom, who normally has command of the troops.

The latest deployments prompted a new wave of misleading images to spread — some purporting to show Marines and the military service’s weapons in action. One was a still from “Blue Thunder,” a 1983 action-thriller about a conspiracy to deprive residents of Los Angeles of their civil rights. It features a climatic dogfight over the city’s downtown.