Under the medical tent at the Boston Marathon.

n engl j med 368;21 nejm.org may 23, 2013 1953 Some volunteers had been staff­ ing the medical tent for years — one nurse had worked at the Bos­ ton Marathon more than 25 times. Sickened and stressed runners poured into our makeshift hos­ pital. A runner stumbled in and vomited into a bag. We helped him onto a cot, where he sat shivering. “You’re OK,” a nurse said gently, wiping his face. But his core temperature had dropped to 96 degrees, and he began hav­ ing violent rigors. We brought him Mylar blankets and hot bouillon. Nearby, a woman with intense hamstring spasms fell onto a cot; a runner with liver disease trembled with asterixis, his eyes roving in wild saccades. Suddenly, there was a loud, sickening blast. My ears were ring­ ing, and then — a long pause. Everyone in the tent stopped and looked up. A dehydrated woman grabbed my wrist. “What was that?” she cried. “Don’t leave.” I didn’t move. John Andersen, a medical coordinator, took the mi­ crophone. “Everybody stay with your patients,” he said, “and stay calm.” Then we smelled smoke — a dense stench of sulfur — and heard a second explosion, farther off but no less frighten­ ing. Despite the patient’s plea, I walked out the back of the tent and saw a crowd running from a cloud of smoke billowing around the finish line. “There are bombs,” a woman whispered. My hands began to shake. I stood outside and called my family. “There are bombs going off here,” I said. Worried but calm, my mother said, “Just take care of yourself and get out of there.” I almost fled, thinking there might be more bombs nearby. There was an exit onto Dartmouth Street, where the crowds were swiftly moving away. But from within the tent I heard Ander­ sen’s voice, an echo of my own conscience: “All medical person­ nel stay with your patients.” His straightforward, controlled in­ struction appealed to some deep conviction reinforced by my med­ ical training. When I reentered the tent, the patient who’d grabbed my wrist was gone. My friend Jennifer Schwartz was looking for her stethoscope — “I can’t find it,” she said, distressed. A nurse standing between cots be­ Under the Medical Tent at the Boston Marathon