Husband of Texas Teacher Killed Protecting Her Students Dies 2 Days Later: 'Broken Heart'

High school sweethearts Irma and Joe Garcia had four children together over their 24-year marriage

The husband of Irma Garcia, one of the two teachers killed in Tuesday's Texas elementary school shooting, has died, PEOPLE learns.

John Martinez, Garcia's nephew, tells PEOPLE that Joe Garcia, Irma's husband of 24 years, died Thursday.

Martinez, 21, says that he believes his uncle Joe, who was 50, died "of a broken heart."

Martinez says he was informed his uncle may have died from cardiac arrest, noting that he was told chest compressions were performed in an effort to revive him.

The couple, he says, had four children together and were high school sweethearts.

Irma, 46, had been a teacher at Robb Elementary School in Uvalde for 23 years.

Irma and Joe Garcia. Go Fund Me

On Tuesday morning, when an 18-year-old gunman wearing body armor entered her classroom with a gun, Irma gave her life trying to save the children she loved like her own.

For more on the shooting massacre at Robb Elementary School in Uvalde, Texas, listen below to our daily podcast PEOPLE Every Day.

"She died a hero trying to protect her students," says Martinez, adding one of the 19 children killed in Tuesday's shooting was found dead in her arms. "She was a mom to them as well."

Irma Rodriguez, John Martinez. Courtesy John Martinez

Adds Martinez: "She was a light in every room. She always had joy in her. She was a light to the world. I just really do want her to be remembered as someone who put her life on the line, to the very last moment. She sacrificed herself."

In 2019, Garcia was named a finalist for the Trinity Prize, which honors local teachers chosen as distinguished educators by Trinity University in San Antonio.

According to her school profile, she loved to barbecue with Joe, and Martinez tells PEOPLE she loved classic rock.

The family has created a GoFundMe campaign to help cover Irma's funeral costs. There is another GoFundMe campaign for both Joe and Irma Garcia.

Irma Garcia. GoFundMe

"She was always optimistic about everything," recalls Martinez, who remembers with fondness turning 21, and enjoying tequila with his Tia Irma. "In her life, she saw the bright side of things. She was one of the funniest people I've honestly really ever met. I mean, there are times where I would just wanna, like, hang out with only her."

Prior to the massacre at the school, the shooter shot his grandmother in the face; the woman has so far survived her injuries.

Before entering the school, the killer crashed his car in a nearby ditch.

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All the fatalities took place inside one classroom, authorities have said.

A responding off-duty U.S. Customs and Border Patrol agent killed the suspect. A motive for the murders, if known, has not been released.

Police said at a Tuesday press conference they believe the shooter acted alone.

All of the children killed were in the second, third, and fourth grades, police have said.

The school district in Uvalde has opened an official account with First State Bank of Uvalde to support Robb Elementary families affected by the tragedy. People can send checks through the mail (payable to the "Robb School Memorial Fund") or donate money through Zelle to [e-mail]. People can also donate by calling 830-356-2273.