"It was law enforcement [that] shot someone, it seems to be the suspect".
Minutes later, Trump reappeared at the press conference and announced that someone had been shot by the Secret Service outside the White House grounds.
When asked whether the incident had "rattled" him, Trump responded casually: "I don't know".
No one else was injured, according to the president, adding that he was taken to the Oval Office when he was evacuated.
When he returned shortly afterwards, the president told reporters he believed the US Secret Service had shot an armed suspect. Trump was swiftly whisked away from the podium and later, he returned with an explanation. There was no word on what the threat was and whether the man who was shot was armed.
"It was a shooting outside of the White House", Trump said. Both the suspect and the officer were taken to hospital.
Law enforcement is still on the scene investigating the shooting.
Mr Trump has instituted a series of sweeping immigration restrictions since the start of the coronavirus pandemic, suspending some legal immigration and allowing United States border authorities to rapidly deport migrants caught at the border without standard legal processes.
President Donald Trump said that he wants to host the Group of Seven leading industrialised nations after the November presidential election and still wants to invite Russian Federation, which was kicked out of the G-7 after it annexed Crimea.
Questioned on whether the security incident had rattled him, Trump answered: "I don't know, do I seem rattled?"
Even avowed opponents of the commander in chief, such as Never Trumper Tom Nichols, pushed back against Rubin and others making light of the news, arguing the "safety of the president is not a joking matter", though he did not mention the WaPo writer by name. "They just wanted me to step aside for a little while just to make sure that everything was clear outside".