The first warnings of the earthquake may have occurred at the National Zoo, where officials said some animals seemed to feel it coming before people did. The red ruffed lemurs began “alarm calling” a full 15 minutes before the quake hit, zoo spokeswoman Pamela Baker-Masson said. In the Great Ape House, Iris, an orangutan, let out a guttural holler 10 seconds before keepers felt the quake. The flamingos huddled together in the water seconds before people felt the rumbling. The rheas got excited. And the hooded mergansers — a kind of duck — dashed for the safety of the water.

For people, it was a lovely, sparkling day for an emergency evacuation. Much of the capital’s workforce had gathered on sidewalks by 2 p.m. The federal government later urged agencies to send non-emergency workers home.