The mass shooting in an Orlando, Fla., nightclub early Sunday morning was the most devastating in the history of the United States, causing 49 deaths and wounding more than 50 people. Many of the night’s survivors have spoken out, and victims’ families have shared the heartbreaking last messages of their loved ones. Many people acted heroically during the event, shielding others, helping to bring strangers to safety, and aiding first responders with the wounded. One Orlando doctor gave the internet a look at a medical professional’s role in the aftermath of the night’s tragedy, sharing a photo of his bloodstained sneakers to Facebook.

“On these shoes, soaked between its fibers, is the blood of 54 innocent human beings,” wrote Dr. Joshua Corsa. “I don’t know which were straight, which were gay, which were black, or which were Hispanic.”

Corsa explained that the only thing that mattered was that all of these people had come to the hospital suffering and in need of assistance.

“And somehow, in that chaos, doctors, nurses, technicians, police, paramedics, and others, performed superhuman feats of compassion and care,” he said.

The post has gone viral, with Facebook users sharing the image thousands of times. The doctor wrote that he plans to put the shoes back on until the last shooting victim leaves the hospital. Then, he will take them off and keep them in his office, so he will always remember the night they were stained.

“For on June 12, after the worst of humanity reared its evil head, I saw the best of humanity come fighting right back,” he concluded. “I never want to forget that night.”