WASHINGTON — A Secret Service agent assigned to protect President Joe Biden’s eldest granddaughter, Naomi Biden Neal, opened fire late Sunday as several people were breaking into an unoccupied government vehicle, the agency’s spokesman said Monday.

The agents detailed to her “encountered possibly three individuals breaking a window on a parked and unoccupied government vehicle,” said Anthony Guglielmi, chief of communications for the Secret Service. “During this encounter, a federal agent discharged a service weapon and it is believed no one was struck.”

The individuals immediately fled the scene in a red vehicle, and a regional lookout was issued to supporting units, he said.

“There was no threat to any protectees and the incident is being investigated by the D.C. Metropolitan Police Department and the Secret Service,” Guglielmi said.

He didn’t provide any additional details about the circumstances of the incident.

Read Related Also: Target offering Thanksgiving meal for under $25 – here's what comes with it

A source familiar with the investigation confirmed to NBC News that the Secret Service agents had been assigned to protect Naomi Biden.

The incident happened outside her residence in Georgetown. The source did not believe she witnessed any of it.

D.C. police referred all questions to the Secret Service.

Naomi Biden, 29, got married last year to Peter Neal at the White House, the first wedding with a president’s granddaughter as the bride, and the first one in that location, the White House Historical Association said.