One of Monday’s most gripping—and graphic—images was a picture of a young man who appears to have lost both of his legs, being frantically wheeled to an ambulance by responders. On Twitter, there’s been a lot of discussion about the ethics of running the picture without blurring the young man’s face, as The Atlantic did for over an hour on its site before altering the image. The Washington Post chose to crop the image so the victim’s legs are visible only above the knee.

One of the responders in the photograph—the man in the cowboy hat—has been identified as Carlos Arredondo, a Costa Rican immigrant (originally undocumented) whose Marine son died in action in Iraq in 2004. The day he learned of his son’s death, Arredondo ?locked himself in a van with five gallons of gasoline and a propane torch and set the van on fire. He survived, became a peace activist, and was among the spectators who rushed toward the fumes after the explosion today. After tying a tourniquet onto the young man’s legs and wheeling him past the finish line to emergency help, Arredondo, seen badly shaken and trembling in this video, gripping a small American flag drenched in blood, talks to some bystanders on the street about the explosion:

Arredondo was at the marathon to cheer for a runner who’d dedicated their race to his son. In 2011, Arredondo’s other son, Brian, 24, committed suicide after suffering years of depression and drug addiction following his brother’s death. You can see the 52-year-old, cowboy-hat-clad activist in the immediate aftermath of the attack at the 2:00 mark below, lifting pieces of broken fence and debris away from victims lying on the sidewalk:

Over on Reddit, there’s a post from someone who says they’re a friend of the victim in the wheelchair, and that he found a record of his friend—Jeff—through Google’s Person Finder, an app for locating loved ones after an emergency. The app said Jeff “was in the Boston Medical Center ER as of 23:20 UTC.” The thread also has a Facebook message from someone asking for prayers for his son, Jeff Jr., who was injured in the blast:

Can everyone pray for my Son Jeff jr who was at the finish line today in Boston. He is in surgery right now with injuries to his legs. I just can’t explain whats wrong with people today to do this to people. I’m really starting to lose faith in our country.

The Redditor added an update to say Jeff is in stable condition, and that “Carlos Arredondo should never have to buy a drink in this town again.”