Sen. Elizabeth Warren announced her oldest brother, Donald Reed Herring, died Tuesday night after being infected with the coronavirus. 

"My oldest brother, Don Reed, died from coronavirus on Tuesday evening," Warren said in a tweet. "He joined the Air Force at 19 and spent his career in the military, including five and a half years off and on in combat in Vietnam. He was charming and funny, a natural leader.

"What made him extra special was his smile – quick and crooked, it always seemed to generate its own light, one that lit up everyone around him." 

The Boston Globe reported that Herring, 86, tested positive for the coronavirus about three weeks ago. He was taken to Norman Regional Hospital in Norman, Oklahoma, on April 15, where he died six days later. 

Warren expressed gratitude to the nurses and other medical professionals who treated her brother. 

"But it’s hard to know that there was no family to hold his hand or to say 'I love you' one more time – and no funeral for those of us who loved him to hold each other close," she said. 

"I'll miss you dearly my brother." 

What made him extra special was his smile—quick and crooked, it always seemed to generate its own light, one that lit up everyone around him.pic.twitter.com/SFMOaBVCN3

— Elizabeth Warren (@ewarren)April 23, 2020

Like Herring, many struck by the coronavirus have died without loved ones at their side due to rules meant to stop the spread of infection. Herring's family told the Globe he was moved to an inpatient facility to recover from a bout of pneumonia he suffered in February. That facility discovered there were active cases among its patients and a test confirmed Herring was one of them. 

His wife, Judith Anne Hart, was unable to visit him in recent weeks. Warren said she spoke to him almost every day before he was moved to the hospital, but it became tougher as his condition worsened. She told the Globe she last spoke to him Sunday. 

Herring was a B-47 and B-52 bomber pilot who flew 288 combat missions in Vietnam, according to The Globe. After 20 years in the Air Force, he retired as a lieutenant colonel in 1973 before opening an auto-detailing business. 

"I’m heartbroken for my friend Elizabeth Warren and her family. My prayers go to them," said Senate Minority Leader Charles Schumer. "I’m heartbroken too many Americans are fighting through this grief and aren’t able to be with their family members to hold their hands and tell them they love them. I’m so sorry, Elizabeth." 

I’m heartbroken for my friend Elizabeth Warren and her family. My prayers go to them.

I’m heartbroken too many Americans are fighting through this grief and aren’t able to be with their family members to hold their hands and tell them they love them.

I’m so sorry, Elizabeth.https://t.co/v4azh7ahdT

— Chuck Schumer (@SenSchumer)April 23, 2020

Warren, a former 2020 Democratic presidential candidate, has been a fierce critic of President Donald Trump's response to the COVID-19 pandemic. When she was still a candidate at the end of January, she announced her plan to prepare for pandemics and said, "Like so much else, Trump’s approach to keeping us safe from disease outbreaks is a mess."

On Wednesday, she called for an investigation into Trump's handling of the crisis. 

"He's misled the public from the start. He's allocating resources based on which governors he likes best. His family and their cronies are making policy decisions in backroom deals. Enough is enough. We need an investigation into Trump's pandemic response," she said. 

Last month, Minnesota Lt. Gov. Peggy Flanagan's brother died from COVID-19.

Six members of Congress have tested positive for the coronavirus since the outbreak began and others have had loved ones become infected. 

The husband of Sen. Amy Klobuchar, D-Minn., was released from the hospital last month after contracting COVID-19. And on Thursday, while debating a nearly half-trillion measure to revive a small business loan program, Rep. Maxine Waters, D-Calif., said her family was also suffering. 

"I'm going to take a moment to dedicate this legislation to my dear sister who is dying in a hospital in St. Louis, Missouri right now, infected by the coronavirus," she said on the House floor, her voice cracking. 

Contributing: Christal Hayes