Irma Garcia was killed protecting her students. Her husband died two days later: "Joe died of a broken heart."

Fourth-grade teacher Irma Garcia was one of two faculty members killed on Tuesday during a mass shooting at Robb Elementary in Uvalde, Texas. On Thursday morning, her husband and high school sweetheart Joe died from what family members said was a "medical emergency." 

"I truly believe Joe died of a broken heart," Irma Garcia's cousin Debra Austin wrote on a GoFundMe page. "Losing the love of his life of more than 25 years was too much to bear." 

One of the couple's nephews tweeted that Joe Garcia died after suffering a heart attack at home. 

"These two will make anyone feel loved no matter what," he tweeted. "They have the purest hearts ever i love you [so much] tia and tio please be with me every step of the way." 

Joe Garcia was 50 years old and had just gotten home from leaving flowers at his wife's memorial when he "pretty much just fell over," his nephew, John Martinez, told The New York Times. 

CBS News has reached out to the Garcia's family members for further information.

Martinez wrote on Twitter that his uncle had "passed away due to grief." 

"I truly am at a loss for words for how we are all feeling," he said. "...God have mercy on us, this isn't easy." 

Dying from grief, known as broken heart syndrome, is caused by a surge of stress hormones, according to the American Heart Association, that is usually caused by an emotionally stressful event. The death of a loved one is a common reason for the stress-induced cardiomyopathy. 

According to the association, it is often misdiagnosed as a heart attack because of similar symptoms. Both attacks display a dramatic change in rhythm, but there are no blocked arteries in broken heart syndrome. 

Martinez said the couple were high school sweethearts and have four children, ages 23, 19, 15 and 13. 

"No child should have to go through this," Martinez tweeted. "My heart breaks for them." 

A fourth-grader who survived Tuesday's shooting told CBS affiliate KENS-TV that Irma Garcia and another teacher who was killed, 44-year-old Eva Mireles, saved his and other kids' lives. 

"They were in front of my classmates to help," he said. "To save them." 

Following Tuesday's shooting, Martinez said that his aunt "sacrificed herself protecting the kids in her classroom." 

"Irma Garcia is her name," he said, "and she died a hero." 

In:
• American Heart Association
• School Shooting
• Heart Attack
• Texas
• Mass Shooting