Jose Rafael Guzman, 27, was booked for criminal threats and threatening a public officer, the Long Beach Police Department said. He was released after posting $50,000 bail.
"We take all potential threats of violence very seriously and thoroughly investigate all reported incidents," said Police Chief Robert Luna. "Our department will remain vigilant and continue to be visible to ensure the safety of our community."
The investigation began Sunday after a "concerned community member" notified authorities of the alleged threat, officials said. Detectives later identified Guzman as a suspect and then arrested him at his home in Huntington Park.
Sanders is set to appear at a 7 p.m. event Tuesday at Long Beach City College, according to his campaign's official website.
Police say in light of the recent mass shootings across the country, officers will be more vigilant.
"Due to recent events that have occurred nationally the Long Beach police department is taking a stronger posture against violence and we're putting more officers out on the street, making officers more visible," said Long Beach police Lt. Lee Debrabander.
Anyone with information about a threat of violence is asked to call 911 or Long Beach police at (562) 435-6711.