Two law enforcement sources told CNN that the wounded person was unarmed.

The White House complex, the Secret Service said, was not breached during the incident "and no Secret Service protectees were ever in danger."

The Secret Service Office of Professional Responsibility will conduct an internal review of the officer's conduct, the statement added.

The incident interrupted Trump's briefing in rarely seen fashion.

Trump had been midsentence during the first attempt at a briefing when security came into the room and asked him to leave the area.

"Excuse me?" Trump asked when the security approached.

"Step outside," the agent said.

"Oh," Trump said before departing the room.

When Trump returned to the briefing room, he said he has been taken to the Oval Office when he was evacuated.