Maryland Gov. Larry Hogan said Thursday that three people from Montgomery County have been diagnosed with the coronavirus: a husband and wife in their 70s and a woman in her 50s.

Hogan (R) declared a state of emergency to speed the delivery of funding and other resources to address the virus. So far, no cases of the coronavirus have been diagnosed in Virginia or the District.

The three patients contracted the virus while traveling overseas and are “in good condition,” Hogan said. They are quarantined in their homes in the county, a large and affluent suburb of about 1 million people just outside Washington. The woman is not related to the couple.

“We have been actively preparing for this situation over the last several weeks across all levels of government,” Hogan said. “I encourage all Marylanders . . . to take this seriously and to stay informed as we continue to provide updates.”

As of Thursday morning, 31 Maryland residents had been tested for the coronavirus. Seventeen of the tests were negative, according to the Maryland Department of Health’s website page that is tracking the virus. The rest were pending.

At a news conference at the State House in Annapolis, Hogan urged residents to remain calm. “While today’s news may seem overwhelming, this is not a reason to panic,” Hogan said. “Marylanders should go to school and work, just as they normally do.”

Fran Phillips, Maryland’s deputy secretary for public health, said the three people returned to Maryland from the same overseas trip on Feb. 20. Officials declined to specify where they had traveled. Montgomery County Executive Marc Elrich (D) said he was told by an aide to Hogan that the individuals were on a cruise.

Travis Gayles, the county’s health officer, said the individuals sought medical attention “fairly immediately” after returning home. But their travel had not involved China, the only country at that time that had been flagged as a place that should trigger testing for the virus.

So, they were not tested upon their return, Gayles said.

This week, the Centers for Disease Control and Prevention learned that people on the trip that the Montgomery County residents had taken may have been exposed to the coronavirus. The residents were contacted by the state’s health department and were told they should be tested.

The three patients “were out and about because their travel wasn’t flagged,” Hogan spokesman Mike Ricci said. The investigation will look at their comings and goings, “where they went and who they interacted with.”

Phillips said the three had “flu-like” symptoms but that none was seriously ill. They were able to bring themselves to a hospital Wednesday, and they arrived wearing “protective precautions.”

Specimens were collected and they returned home. They were each mildly to moderately ill, and their symptoms are abating, Phillips said.

Maryland received the results Thursday. State and county health officials and the CDC are conducting a broad investigation of the cases, in part to determine who else may have been exposed in the days between the victims’ arrival home and when they were tested.

“We want to understand all of the activity, all of the comings and goings of these individuals.” Phillips said. “They have been extraordinarily cooperative. We want to understand the period of time when they returned from travel and when they had symptoms ... We want to understand where they went and who they interacted with, in order that we can conduct this investigation.”

The patients are not believed to have had any contact with children, she said. Montgomery County Public Schools said Thursday night that schools would be open as usual on Friday.

Elrich is holding a news conference Friday morning that will be live-streamed at montgomerycountymd.gov and on Facebook.

For weeks, elected officials in the region have been meeting with their public health departments, emergency management teams and top lieutenants in anticipation of what many said was the inevitability of confirmed cases of the disease.

As medical professionals prepared for the possibility, they made sure they had plenty of masks and other protective equipment for first responders and others who would be on the front lines of caring for patients.

Twenty-one Virginia residents had been tested as of Thursday, including 18 whose tests came back negative and three that are pending. None of the pending cases are in Northern Virginia. Eight D.C. residents have been tested; six tests came back negative, while two are pending.

About 70 miles west of Washington, Wakefield Country Day School near Huntly, Va., kept its 132 students home Thursday and Friday as a precaution after a group of students and adults recently visited Italy, France and Switzerland.

The school was on winter break last week, then students who traveled to Europe stayed home this week before officials closed the school for two days. The group departed Feb. 20 and returned five days days later. No students have shown signs of illness.

Head of school Jessica Andrus Lindstrom said by the time the school reopens Monday, students who went to Europe will have been away for the 14-day quarantine period recommended by the CDC.

In Maryland, the General Assembly has fast-tracked a request from the governor to access $50 million from the state’s rainy day fund to deal with the coronavirus. The legislation was advanced by the Senate Budget and Taxation Committee on Thursday and is pending in the House Appropriations Committee. It will be considered by the full Senate on Friday.

Hogan also submitted a supplemental budget request for fiscal 2021 that would allocate $10 million in emergency expenses to prepare for the coronavirus. Part of the spending would be used to purchase equipment for rapid diagnosis, additional staff for investigations and providing services for quarantined individuals, including food and medicine.

The state’s health department and the Maryland Institute for Emergency Medical Services Systems are coordinating on surge planning, including ambulance rerouting plans, suspension of voluntary hospital admissions and enhanced medical monitoring for homebound patients with mild to moderate symptoms.

Anxiety about the global coronavirus outbreak has catapulted health care to become a top concern for many Maryland residents, according to a poll released late Wednesday.

Since January, the number of residents who described health care as their top concern tripled to 17 percent, the Gonzales poll found, second only to the percentage of people who are most worried about crime.

Fears over the threat of covid-19, the disease caused by the novel coronavirus, fueled the change, pollster Patrick E. Gonzales said.

The Montgomery County Council received a briefing Tuesday on preparation efforts in the county.

“From what we heard, the county is as prepared as it can be under the circumstances,” said County Council member Gabe Albornoz (D-At Large), chair of the council’s health committee.

Council Vice President Tom Hucker (D-District 5) said he was particularly concerned about exposing the county’s large immigrant population to the virus.

“We have a very diverse population of undocumented residents who have understandable fears now of interacting with government agencies,” said Hucker, whose district includes densely populated Silver Spring.

He cited the recent public charge rule, which advocates say has made some immigrant families fearful of seeking medical care. “It’s very important that these folks know in Montgomery, they’re safe, and they should seek medical attention right away if they have symptoms,” he said.

Erin Cox and Dana Hedgpeth contributed to this report.