The number of people in the District dying outside hospitals spiked as the novel coronavirus started its sweep through the nation’s capital, raising concerns that people suffering a wide range of critical ailments are not seeking medical attention.

Some of those people contracted the virus; the city has so far confirmed such deaths at home for three residents. But officials suspect many of the deaths are not related to the virus and may be the result of heart attacks, drug overdoses or other causes.

Tests are still pending in most of the cases, and a clear picture of the deaths might not be known until at least July.

The deaths occurred in private residences and other buildings, including nursing homes, and outdoors. They are people who were deceased when first responders arrived at a call or could not be resuscitated before being rushed to emergency rooms.

Doctors at hospitals have noticed a dearth of patients who once filled their cardiac wards and other treatment wings. “They are worried those patients are not seeking their care and are finding themselves in my care,” said Roger A. Mitchell Jr., the District’s chief medical examiner.

From March 1 through April 15, D.C. officials say, 138 people were pronounced dead on the scene, a 74 percent increase over the same period in 2019. The District’s first confirmed coronavirus case was reported March 7, though new testing shows the virus could have been circulating weeks earlier.

Among those who died outside the hospitals in the District from early March through mid-April were 61 people treated by paramedics responding to calls for heart-attack victims. Paramedics have seen more calls for cardiac arrests compared with the same period last year, and fewer of those patients are surviving — 42 percent in recent weeks compared with 60 percent in the same period last year.

New York City has seen a similar phenomenon. From March 20 through April 5, fire officials there said, paramedics responded to more than 300 cardiac-arrest calls each day, with two-thirds of the patients dying at the scene. They said they saw fewer such calls and a higher survival rate during the same time last year.

The deaths in the District also include homicides, suicides and drug overdoses. Mitchell said during those six weeks that there were fewer homicides and suicides than occurred during the same period the previous year.

The situation appears to mirror a national trend. The Washington Post has reported that the United States recorded 37,100 excess deaths — beyond what would normally be expected — from the beginning of March through mid-April, nearly 13,500 more than are now attributed to covid-19 for the same period.

More than 67,000 people across the country have died of covid-19, with over 1.1 million confirmed cases, though it is widely believed those numbers are an undercount. Jurisdictions count cases and deaths differently. Some include probable cases, even if testing is not performed, and few test the dead.

The D.C. medical examiner’s office did not immediately have a demographic breakdown on the deaths occurring outside hospitals to include the race or ages of the deceased.

Nearly 80 percent of the District’s 258 known deaths from covid-19 are of African Americans, and the virus is hitting hard in wards disproportionately affected by poverty, disease and trauma. D.C. officials fear the spike in on-scene death cases might be affecting the city’s most vulnerable populations in similar ways.

“I think where we have had divisions and inadequacies in our city, the pandemic magnifies them,” said Kevin Donahue, the deputy mayor for public safely.

Donahue said officials believe some people may be putting off needed treatment because they are scared of contracting the coronavirus at a hospital. Many routine procedures, and some more-urgent ones, have been postponed during the pandemic.

Mayor Muriel E. Bowser (D) discussed the city’s at-risk population at a Monday news conference during which she updated residents on the pandemic. She emphasized that hospitals remain open to treat illnesses and emergencies that have nothing to do with the coronavirus and are safe to visit.

“It’s kind of a mixed message in some ways because we’ve told everyone to stay home, but that doesn’t mean stay home if we need medical care,” Bowser said.

D.C. Health Director LaQuandra Nesbitt described symptoms of heart attacks and strokes, and she put up a slide reminding people that “every minute counts” in a medical emergency and that they should not hesitate to call 911.

“We will be well prepared to take care of them,” Nesbitt said.

D.C. officials say hospital capacity is adequate, though preparations are underway for a possible surge. The Army Corps of Engineers has transformed the Walter E. Washington Convention Center into a makeshift hospital, with the hope it will not be needed.

Even as the number of coronavirus cases and deaths ticks up, the District’s 911 center is fielding fewer calls than usual. Requests for ambulances are down 16 percent this year, and emergency calls that typically number about 6,700 over a two-week period have fallen by about 1,000. Donahue attributes that to “all the people on lockdown.” Also, the District’s population, which once doubled on an average weekday, taking into account commuters, federal workers and tourists, is now without many of those people.

But even if the District’s paramedics are responding to fewer calls, they are encountering more bodies than normal. And the medical-examiner workers who investigate and transport those bodies are taking extra precautions.

Typically, the medical examiner’s office is notified about a death from a hospital or, if it occurred in a private home or elsewhere, from police or paramedics.

If a death is outside the hospital, the medical examiner dispatches an investigator in addition to the transport crew. D.C. police also typically send investigators from the homicide unit’s natural-death squad.

Because of the coronavirus, the medical-examiner crews now do advance work before responding. Hospital staffs inform them if the patient tested positive for the virus. In a home, paramedics or police question loved ones about the patient’s history. If covid-19 is confirmed or suspected, the medical examiner’s crew shows up in full protective gear, places the victim inside two body bags and sanitizes the coverings — protocols already in place for handling infectious diseases.

If a person has tested positive, Mitchell’s staff records it as a coronavirus death, with no need for further testing.

Tests that can produce results within 24 to 48 hours are conducted on bodies in which covid-19 is suspected, such as when family members say the victim exhibited symptoms including a cough, fever or labored breathing. Mitchell said he tests bodies of people with histories of pneumonia and sometimes X-rays chests of the deceased to check lungs. If the lungs show signs of infection, his office conducts a coronavirus test.

Mitchell said those procedures will help the District eventually build a fuller portrait of the pandemic’s devastation. “We are going to have an extremely clear picture of it,” Mitchell said.

The three at-home covid-19 deaths already announced in the District occurred the last weekend in March and were noted by Bowser, who, without providing details, urged residents to seek medical care regardless of their immigration status. Officials later said one of those victims was a man who died after he declined assistance from D.C. paramedics.

Mitchell stressed that he is awaiting test results in many of the other on-scene death cases and that he did not want to speculate on their causes.

Last week, Bowser reached agreements for hospitals to replace United Medical Center, serving the poorest wards east of the Anacostia River, and Howard University facilities, a boost to providing health care to African American areas of the city and addressing problems that existed before the pandemic.

Mitchell noted historic inequities in health care, which the pandemic has brought into sharp focus in the District and elsewhere, and the need, the medical examiner said, for all residents to “have the same access to care.”

Fenit Nirappil and Emma Brown contributed to this report.