The collision occurred after the driver of a Toyota Highlander turned left in front of the motorcade.
The incident happened at 7:22 p.m. along Madera Road near Aristotle Street, California Highway Patrol spokeswoman Elizabeth Kravig told ABC News.
The driver, a female, and her son were taken to a hospital, as was a California Highway Patrol officer, KABC's Jory Rand reported. The office was escorting the motorcade.
Kravig told ABC News that the CHP officer had "non-critical" injuries. The condition of the woman and her son is unknown.
The Highlander driver's husband, Michael Sternberg, was in the vehicle with his wife at the time.
"She was concerned about our son's wrists that might be broken and her neck, she was in a lot of pain," he told KABC.
In regards to the collision, Sternberg said of his wife, "She saw one motorcycle pass and she was not aware of the other motorcycles."
Trudeau's motorcade eventually continued on its way, and the Canadian lawmaker was not hurt, reported KABC. The car carrying Trudeau was not involved in the collision.
The collision occurred about four miles from the Reagan Presidential Library, where Trudeau had just left, following a speaking engagement there on U.S.-Canada relations.
ABC News has reached out to Trudeau's office for comment.