A pattern emerges in the first 100 deaths nationwide.

Coronavirus has killed from coast to coast. It devastated a nursing home in Washington state and crept into the heartland. Across the United States, at least 100 people infected with the highly contagious new virus have now died — a toll that experts expect to rise quickly.

This country’s first fatal cases offer a preview of the challenges ahead, as Americans battle a disease that has killed thousands of people worldwide. The Washington Post has tracked every known U.S. death and has analyzed data provided by state and local health officials, families of the victims and the Centers for Disease Control and Prevention.

Of the first 100 reported fatalities, many people appear to have had underlying health conditions, making it harder for their bodies to fight off COVID-19, the disease caused by the novel coronavirus. Some had diabetes, kidney failure, hypertension or pulmonary ailments.

Nearly all — about 85 percent — were older than 60, and about 45 percent were older than 80. It’s unclear how some of them contracted the disease, but more than a third were living in residential care facilities when they became ill.

What is known about the scale of transmission and the high number of deaths among vulnerable populations — like at the Life Care Center of Kirkland in Washington state, where 27 of the facility’s 120 residents have died — has experts deeply concerned.

“I see that as the ‘canary in a coal mine’ situation,” said Fred Buckner, an attending physician at the University of Washington Medical Center. “I suspect it’s going to be taking off in other locations just like it is in the Seattle area. There’s no reason not to think that. Obviously, that means more deaths.”

In addition to the cluster of cases at Life Care Center, health authorities are monitoring cases at Lambeth House

Retirement Community in New Orleans, a high-rise with about 250 residences and rooms. Of the four people who have died in New Orleans, two had been at Lambeth, where 12 cases are confirmed, Louisiana Gov. John Bel Edwards said Monday.

Caitlin Rivers, an epidemiologist at Johns Hopkins University in Baltimore, said: “One particularly unsettling aspect of the outbreak (at Life Care Center) is the number of residents who have gotten sick and died in that facility. That’s a very high fraction.”

The early profiles of those who have fallen victim to COVID-19 should be “a reminder that this virus can be very dangerous,” Rivers added. “It should serve as additional motivation to take every opportunity to reduce transmission.”

Darlene Kimball, 72, was one of those who died of COVID-19 after a stay at Life Care Center. The avid gardener, animal lover and grandmother of five had been living with ovarian cancer for four years when she fell in mid-February and went to Life Care Center for rehabilitation, said her daughter, Tami Kahler.

Kimball at that point was lucid, talkative and mobile. She was in the process of finding a new oncologist.

But at Life Care Center, she developed a cough, becoming increasingly raspy and finding it difficult to breathe. While visiting Kimball — who was surrounded by her children, grandchildren and friends “24 hours a day,” Kahler said in an interview — family members noticed that many of the facility’s residents appeared to be sick. When Kimball began complaining of chest pains in late February, they urged a nurse to call the hospital.

It was only after the doctors and nurses had started wearing masks and gowns in Kimball’s presence; after her pneumonia was diagnosed and she was transferred to hospice care; and after the family pleaded for a coronavirus test that Kahler said her mother got one.

“They got the results back on Thursday,” March 5, Kahler said. “She died Friday.”