After he returned to continue his coronavirus response briefing, Trump said he had been taken to the Oval Office by the Secret Service and told reporters that law enforcement had shot someone outside the White House.
"There was a shooting, law enforcement shot someone, seems to be someone, and the suspect is on the way to the hospital," Trump said as the briefing restarted following the sudden, but brief, lockdown.
The incident, on 17th Street and Pennsylvania Avenue, did not threaten any Secret Service protectees, nor was the White House complex breached, law enforcement officials said.
"The suspect approached the officer and told the officer he had a weapon," Secret Service Uniformed Division Chief Tom Sullivan told reporters late Monday. "The suspect then turned around, ran aggressively towards the officer, and in a drawing motion, withdrew an object from his clothing. He then crouched into a shooter’s stance as if he was about to fire a weapon. The Secret Service officer discharged his weapon, striking the individual in the torso."
Sullivan declined to answer reporters' questions about what the object was.
According to another source familiar with the matter, the Secret Service called for an ambulance at 5:55 p.m. and one came shortly after. The suspect, described as a 51-year-old male, was transported to a hospital in critical condition with one gunshot wound to the upper body, the source said.
Earlier Monday, a source told ABC News that the suspect opened fired on a non-White House employee. Trump also said during the briefing that "from what I understand" the suspect was armed. He said the suspect was shot outside the White House grounds but close to the fence.
"It's unfortunate that this is the world, but the world has always been a dangerous place. It's not something that's unique," he added.
In addition to the Secret Service, the Metropolitan Police Department was assisting with the investigation.
The president was taken out of the briefing room and into the Oval Office for about nine minutes.
"We don't know" if the suspect mentioned a name, he said. "It might not have had anything to do with me."
Trump said he "didn't even think about not coming back" to brief reporters.
Asked what the Secret Service agent told him when he was approached mid-sentence, Trump said, "Just told me when he came up, you pretty much saw it like I did. He said, 'Sir, could you please come with me?' So, you were surprised. I was surprised, also. I think it's probably -- it's pretty unusual but very, very professional people, they all do a fantastic job, as you know."
Responding to a question from reporters, Trump said he does not think the suspect "breached anything."
"It was on the outside grounds, so I don't believe anything was breached. I asked that question. They were relatively far away," Trump said.
ABC News' Luke Barr and Jake Date contributed to this report.