Trump makes 'surprise visit' outside hospital

U.S. President Donald Trump made a surprise drive-by greeting for cheering supporters outside Walter Reed hospital on Sunday.

It was his first public appearance since being evacuated there on Friday, after testing positive for COVID-19.

Trump wore a mask as he waved from the back seat of a black SUV, part of a motorcade that crawled past crowds of people waving Trump 2020 flags and chanting 'four more years.'

Trump announced earlier on Twitter he had planned "a little surprise" for his fans gathered outside.

But critics slammed Trump's appearance, with Dr. James Phillips, an attending physical at the hospital, writing on Twitter Sunday that quote "The irresponsibility is astounding."

Phillips says that personnel who traveled in Trump's armored SUV would now have to self-quarantine for 14 days.

Trump also says he's met soldiers and first responders at the hospital, raising new questions about whether he was now directly exposing others to the virus -- a growing list of Trump allies and aides have also tested positive.

However, White House spokesman Judd Deere said the trip had been approved by medical staff and that appropriate precautions had been taken.

Trump's illness has upended his campaign just a month ahead of the election on November 3 against Democratic opponent Joe Biden.

Biden, who has so far tested negative after sharing a debate stage with Trump last week, has wished the president a speedy recovery, while also criticizing his response to the pandemic.

Meanwhile Trump's campaign vowed that Vice President Mike Pence, who would assume the presidency if Trump were unable to carry out his duties, would have an "aggressive" campaign schedule this week, as well as the president's three oldest children.

Pence, who tested negative on Friday, is scheduled to debate Democratic vice presidential nominee Kamala Harris on Wednesday.