Following those who fled in fear were the helpers.

On Monday, Jarrett Peper, a receptionist at the center, arrived at work just before 8 a.m. and there were already supplies for people who had taken shelter. As the morning wore on, there were piles of blankets and donations of coffee and doughnuts.

“It was packed,” said Ms. Peper in a telephone interview. “All morning, blankets, food and water, all kinds of people coming up to help.”

“It’s incredible, absolutely incredible,” she said of the response. “When there is a tragedy like that, everybody cares and it brings everybody together.”