WASHINGTON (AP) — An investigation is underway after a Secret Service agent working on protective assignment outside Treasury Secretary Janet Yellen's house fired a weapon following a confrontation between the agent and occupants of a sedan, early Tuesday.

At roughly 1:30 a.m. Tuesday, the agent assigned to Yellen's protective detail outside of her home, observed a sedan with multiple people attempting to open car doors along the street, according to Secret Service spokesman Anthony Guglielmi.

A confrontation between the agent and the car's occupants led to gunfire. It was unclear how many shots were fired by the agent. The Secret Service said there is no evidence that anyone was harmed.

The suspects fled the scene in the sedan, and a lookout was issued to local law enforcement, Guglielmi said.

The D.C. Metropolitan Police Department is investigating the shooting and the case will also be reviewed by the U.S. Attorney’s Office.