A United States Secret Service agent was robbed at gunpoint in Southern California over the weekend, on the same night that President Joe Biden was in Los Angeles for a re-election fund-raiser, the authorities said on Monday.

Police officers were called to a residential development in Orange County at about 9:36 p.m. on Saturday over reports of a possible robbery, the Tustin Police Department said in a statement.

Upon arriving at the development — a former military base — the police discovered that the victim was a Secret Service agent whose bag had been stolen at gunpoint, the statement said. During the robbery, an agent fired a gun, the police added.

The suspected robbery occurred on the same night that Mr. Biden was in downtown Los Angeles for a star-studded re-election fund-raiser with former President Barack Obama. Celebrities including George Clooney, Julia Roberts and Barbra Streisand attended the gala, which the Biden campaign said raised at least $28 million.

It was not immediately clear if the Secret Service agent was in California protecting Mr. Biden or Mr. Obama. The police statement did not identify the agent. The Tustin Police Department did not immediately respond to requests for clarification.

It was unclear how many suspects were involved or if they were injured during the shooting, the statement said, adding that no suspects had been found. The police were able to locate some of the agent’s belongings in the area.

The U.S. Secret Service did not immediately respond to requests for comment.