Carlos Arredondo was waiting at the Boston Marathon finish line for runners who were racing on behalf of fallen soldiers—one of those fallen soldiers being Arredondo's son—and handing out American flags when the blast went off across the street. He ran to help injured spectators, including one man whose legs were blown off. Arredondo can be seen, wearing a cowboy hat, in an iconic photo in the gallery (warning: It's graphic), apparently holding the man's severed artery, NBC News reports. "I kept talking to him. I kept saying, 'Stay with me, stay with me,'" Arredondo tells Maine's Portland Press Herald.
Another widely-circulated photo shows Arredondo, who is reportedly a Red Cross disaster team member, carrying one of his American flags, soaked with blood. But this is far from the first tragic twist in Arredondo's life, as NBC News points out after delving through past media coverage of the Costa Rica native. He lost his son, Marine Lance Cpl. Alexander Arredondo, during the 20-year-old's second tour of duty in Iraq in 2004. Arredondo got the news on his 44th birthday, and immediately climbed inside the Marine Corps van and set it afire, burning himself severely. He became a peace activist and started sharing his son's story via a mobile memorial in his pickup truck that he drives around the country, and in 2007 he was beaten at a Washington anti-war demonstration. Four years later, his other son, Brian, killed himself at 24. He had struggled with depression and drug addiction after his brother's death, Mother Jones reports; he was facing jail at the time of his suicide. "We are broken people," Arredondo told the Boston Herald last year. But today, he's "a real hero," a bystander tells ABC News. "He jumped right over the fence even before there were police and tried to help people." (Read more Carlos Arredondo stories.)