Lawrence Riley was an iron man. The 66-year-old Milwaukee resident was a U.S. Navy veteran, a retired firefighter and had survived two strokes.

His family thought he could beat anything.

"The way he handled pain, he was a tough guy. For this to take him out, it was a shock," his son, Elvaughn Riley, told ABC News in a telephone interview.

The elder Riley died last Thursday, two days after he tested positive for novel coronavirus.

His family said he had been feeling under the weather days before. What started as just feeling tired and drained over the weekend turned into Riley being bedridden by Monday, according to his son.

Come Tuesday, his family rushed him to the hospital, where he was placed in a medically induced coma and confirmed infected with coronavirus.

Two days later, he died.

There are over 52,000 confirmed cases of coronavirus in the United States and at least 677 deaths, according to data by Johns Hopkins University.

The virus is believed to be more dangerous for older people. Out of the deaths in the U.S., about 80% were adults over the age of 65, according to the Centers for Disease Control and Prevention.

Elvaughn Riley, 28, said his family is trying to come to terms with their father's death, but they haven't been able to grieve properly.

When his dad was admitted, his mom, younger sister, and younger brother were all told to quarantine inside their home in an effort to stop further spread. Riley lives elsewhere and has not been able to see them. He leaves food and supplies at their front door.

And when their dad had passed, they weren't able to be with him.

"We weren't even there to comfort him, to hold his hand," Riley said. "He died alone."

His relationship with his dad had always been special, he said. Hearing stories from his father's time in the Navy during the Vietnam War inspired Riley to sign up himself.

While he served, he ended up having the same job as his father: aviation maintenance administration.

"I looked up to him so much. Me joining the Navy was an easy decision. The kind of man my father was, I wanted to be like that," Riley said.

He described his dad as someone who would take anyone in that needed it and was a father figure to many of his friends who grew up in a single-parent home.

Whitley Riley, the youngest and only daughter in the family, similarly described her father as giving.

"He was just really sweet," she told ABC News over the phone. "The sweetest man I've ever known."

Just a year shy of graduating, she had taken extra classes to graduate early so that her dad didn't have to wait until 2022 to see her in a cap and gown.

The 19-year-old Prairie View A&M University student said she's on still track to graduate in 2021, but her father won't be able to be there.

"I was doing all the work and he won't be able to see me," she said.

It isn't the only milestone her father will miss.

On Wednesday, she turns 20 years old.

She and her brother hope their dad's story will serve as a message to others to take the disease seriously. If not for yourself, then for others.

"We need to do everything we can to protect one another. Just because someone the same age as me might not feel the symptoms doesn't mean you can't pass it along," Riley said. "It took my father just like that. I never thought in a million years my dad would be gone in five days."