At the corner of Clarendon Street and Stuart Street, near Copley Square, a woman screamed the name Lisa at intervals, panic on her face as she walked back and forth. Runners, many wrapped in the thin space blankets provided by Boston Marathon officials at the finish line of a race that had ended with two explosions, stood shaking from some combination of runners’ fatigue and shock at what they had heard or seen, or at the bits of news that were passing through the crowd. Some were joined by family members or friends. Some were hugging. Others cried. Many in the crowd stared down at the phones in their hands, trying to make sense of conflicting reports.

A man stood wrapped in a space blanket, shivering, his eyes wide. He had salt caked on his face and neck. Jamie Hoag, who is from Washington, D.C., and grew up outside of Boston, said he was on Boylston Street, just a hundred feet away from finishing his first Boston Marathon—his first marathon of any kind. “An explosion occurred on the left side of the finish line,” he said. “I stopped and just froze—it was an intense explosion. And then a second explosion happened over my left shoulder, about fifty feet away. Pandemonium started breaking out. People started trying to jump over the barriers. The police yelled, ‘It’s an explosion.’ And then they started getting people out of there as fast as possible.”

“The first one, I felt it,” he said. “I thought it was a pyrotechnic display that went afoul. But.