WASHINGTON — A Secret Service agent assigned to protect US President Joe Biden's granddaughter opened fire on suspects attempting to break into an unoccupied government vehicle on Sunday.

Multiple agents on Naomi Biden's detail were in the Georgetown neighborhood of Washington DC.

None of the three suspects are believed to have been hit, according to a Secret Service statement.

A search is on for the suspects who fled the scene in a red car.

"There was no threat to any protectees and the incident is being investigated by the DC Metropolitan Police Department and the Secret Service," the service said in a statement.

The incident occurred on 12 November around midnight local time when Secret Service agents spotted three people breaking the window of an unoccupied government vehicle.

The car was parked outside the home of President Biden's granddaughter, according to anonymous sources cited by US media.

She was not with the agents when the incident occurred although the agents were on duty, the BBC's US media partner CBS reported.

There is no evidence to suggest that the suspects knew the vehicle was part of a protective detail for Biden's granddaughter.

Naomi Biden, 29, is the daughter of Hunter Biden and his former wife Kathleen Buhle, and is the president's eldest granddaughter. — BBC