WASHINGTON (NewsNation Now) — Futures markets tumbled in the early hours of Friday morning after President Trump announced that both he and the first lady tested positive for COVID-19.

Dow Jones Industrial Average futures were down more than 400 points as of 12:30 a.m. The S&P 500 and Nasdaq futures dipped as well.

Trump’s positive test comes just hours after the White House announced that senior aide Hope Hicks had come down with the virus after traveling with the president several times this week. Trump was last seen by reporters returning to the White House on Thursday evening and looked to be in good health. Trump is 74 years old, putting him at higher risk of serious complications from a virus that has now killed more than 205,000 people nationwide.

“Tonight, @FLOTUS and I tested positive for COVID-19. We will begin our quarantine and recovery process immediately. We will get through this TOGETHER!” Trump tweeted.

In a memorandum, the president’s physician said that the president and first lady “are both well at this time” and “plan to remain at home within the White House during their convalescence.”

“Rest assured I expect the President to continue carrying out his duties without disruption while recovering,” he added.

Trump had announced earlier in an interview with Fox News that he and the first lady were awaiting their results.

The diagnosis stands as the most serious known public health scare encountered by any sitting American president in recent history.

Symptoms of COVID-19 can include fever, cough and breathing trouble. Most people develop only mild symptoms. But some people, usually those with other medical complications, develop more severe symptoms, including pneumonia, which can be fatal.