Biden was in Los Angeles for a campaign fundraiser after returning from the G7 meeting in Italy. It was not immediately clear whether the Secret Service agent's work assignment was connected to the president's visit.
The agent was returning from work at the time of the robbery Saturday night and fired a service weapon during the confrontation, but it wasn't known if the assailants were struck, according to a statement by the Secret Service. The agent wasn't injured, the statement said.
The altercation occurred around 9:36 p.m. local time at the Tustin Fields residential community in Orange County. The suspect or suspects weren't located, but a 2004-2006 silver Infiniti FX35 or similar vehicle was seen leaving the scene, Tustin police said.