City officials said there is no evidence that the D.C. man has any connection to the federal government, but they are still investigating who he may have come into contact with over the past few weeks.

Speaking to reporters at his private Florida estate on Saturday night, President Donald Trump said he is "not concerned at all" about coronavirus getting closer to the White House — echoing the optimistic tone he has maintained throughout the crisis. Trump and several members of his cabinet attended the CPAC conference, but the White House says there is "no indication" they "met with or were in close proximity" to the infected participant.

Bowser told reporters Saturday that her office is aware of another person who spent time in D.C. before testing positive for coronavirus at a hospital in Maryland. That person traveled to the area from Nigeria, the mayor said, but she did not give further details.

Bowser added she is not yet planning to cancel any government events or declare a state of emergency.

The public health lab at the DC Department of Forensic Sciences, which diagnosed the D.C. resident, only began testing for coronavirus on Monday. It has analyzed samples from 11 people so far: nine who tested negative, one person whose case is still pending and the man who tested positive. The city lab will now send the sample from that "presumptive positive" test to the CDC for confirmation.

Dr. Jennifer Smith, who leads the D.C. public health lab, said that going forward, it will be able to test about 50 patients per day — though the exact number may vary depending on the number of samples the lab analyzes for each person.

The city is testing people who have symptoms such as a fever or cough and either a history of travel to an affected region or contact with a person known to have coronavirus. It is making exceptions to these criteria on a case-by-case basis, said Dr. Anjali Talwalkar, the senior deputy director of D.C.'s Community Health Administration.

The man who tested positive did not meet the city's testing criteria, but city officials made an exception because his age and underlying health conditions put him at risk.

“The guidelines are just guidelines," Talwalkar said. "This is as much art as it is science.”