President Donald Trump was taken to Walter Reed Medical Center on Friday "out of an abundance of caution" following his coronavirus diagnosis, the White House said.
White House physician Sean Conley said in a statement late Friday that Trump is "doing very well," has started Remdesivir therapy and does not require supplemental oxygen. He added that Trump had completed his first dose of Remdesivir, an experimental antiviral therapy, and was resting comfortably.
Trump also tweeted at 11:31 p.m. ET: "Going welI, I think! Thank you to all. LOVE!!!"
Trump was seen wearing a mask as he departed the White House shortly after 6:15 p.m. ET and walked toward his helicopter, Marine One. He waved to the press but did not stop for questions.
The move, which appears to mark an escalation in the efforts to treat the president, is being made "as a precautionary measure," a senior administration official told NBC News.
"President Trump remains in good spirts, has mild symptoms, and has been working throughout the day," press secretary Kayleigh McEnany said in a statement to reporters at the White House.
"Out of an abundance of caution, and at the recommendation of his physician and medical experts, the President will be working from the presidential offices at Walter Reed for the next few days. President Trump appreciates the outpouring of support for both he and the First Lady," McEnany said.
After his departure from the White House, the president's official Twitter account shared a video of him appearing to speak from the Oval Office.
"I want to thank everybody for the tremendous support," Trump said. "I'm going to Walter Reed hospital, I think I'm doing very well, but we're going to make sure that things work out. The first lady is doing very well. So thank you very much, I appreciate it, I will never forget it. Thank you."
House Minority Leader Kevin McCarthy said that he spoke with Trump Friday night.
The president's transfer to the medical facility comes less than a day after he announced his diagnosis. First lady Melania Trump also tested positive for Covid-19.
Earlier Friday afternoon, the White House physician said Trump was "fatigued but in good spirits." The physician, Dr. Sean Conley, also said Trump, 74, had been given an experimental antibody cocktail treatment, and was taking several nutritional supplements as well.
Conley said the first lady, who turned 50 earlier this year, "remains well with only a mild cough and headache."
The president announced his diagnosis on Twitter early Friday morning. He has since stayed off the social media platform and out of sight, with White House officials providing few updates about his health throughout the day.
NBC, citing three people familiar with his condition, reported Friday afternoon that Trump has a low-grade fever.
The diagnosis has raised questions about the continuity of government if the president is incapacitated. House Speaker Nancy Pelosi, D-Calif., who is second in line after Vice President Mike Pence to assume the duties of the presidency, said earlier in the day that the "continuity of government is always in place."
White House communications director Alyssa Farah assured in a statement to NBC on Friday that "the president is in charge" and that power has not been transferred to Pence.
"It's not necessarily an indication the president's condition has worsened. I think that prudence would want to put him into a place where you have access to facilities, in case his condition does change," former FDA chief Dr. Scott Gottlieb told CNBC.
"What we've seen with patients who are older, with Covid, is they can decompensate very quickly and so it could be that they want to have him in a facility that if, God forbid, he does get worse quickly, they can have medical resources available," Gottlieb said.
-- CNBC's Kevin Stankiewicz and Riya Bhattacharjee contributed to this report.