A man in a "Make America Great Again" hat was arrested Saturday after he allegedly doused demonstrators with bear spray at an anti-Trump rally on Santa Monica Pier in southern California.

David Nicholas Dempsey, 32, was being held Monday without bail pending his initial court appearance, according to the Los Angeles County Sheriff's Department and jail records.

Dempsey was charged with assault with a caustic chemical and violating parole from a prior conviction, the sheriff's department said.

Video from the scene posted on social media and YouTube showed Dempsey walking up to a man who was lying on the ground and spraying him directly in the face at close range, KTLA reported.

Bystanders identified Dempsey as the person who sprayed the bear spray and he was taken into custody at the scene, according to the station.

Saturday’s rally was planned by Refuse Fascism, a group opposed to President Donald Trump and Vice President Mike Pence. Refuse Fascism said on its website that dozens of demonstrators gathered on the beach in the early afternoon holding multicolored fabric to spell out “Trump-Pence #OutNow!” and later marched along the boardwalk and onto the Santa Monica Pier to hold a rally.

"Make America Great Again" is a slogan of Trump's.

Dempsey is next due in court on Oct. 22, jail records show. It is unclear if he has a lawyer.