Reporters heard what sounded like possible gunfire near the North Lawn of the White House Saturday evening, prompting the U.S. Secret Service to move members of the media indoors.

Approximately 20 shots were heard just after 6 p.m. Eastern Time, appearing to originate from the side of the White House complex that contains the Eisenhower Executive Office Building, multiple local and national reporters who were at the White House at the time said.

U.S. Secret Service personnel immediately responded by ushering them inside.

Anthony Guglielmi, a spokesperson for the Secret Service, said in a statement to CBS News that the agency was investigating “reports of shots fired near 17th Street and Pennsylvania Avenue NW” and was working to corroborate the initial details with personnel on the ground.

FBI Director Kash Patel confirmed the bureau’s involvement in a social media post, stating that the FBI was on the scene and actively supporting the Secret Service.

President Donald Trump was inside the White House at the time of the incident, having been on the premises since at least 4 p.m., as reported by White House spokesperson Steven Cheung.

The security alert follows an incident nearly a month ago in which an armed individual breached a security checkpoint outside a Washington, D.C., hotel ballroom hosting the White House Correspondents’ Dinner.

Investigations into Saturday’s incident remain ongoing.