astir

Mieko Kawakamiの 'Breasts and Eggs' を読んでいます。

First a cooking show, then an informercial, but when she hit the news, the screen erupted. You could tell that something really bad had happened. A reporter wearing a grave expression spoke passionately into the camera, hands clamping a microphone. Behind her was a residential area, astir with paramedics and police and a plastic tarp.

"astir" を辞書で調べます。

・Collins Dictionary: moving or stirring, esp. with much activity or excitement: The field was astir with small animals, birds, and insects
・Cambridge English Dictionary: out of bed and moving around, or in an excited state: After the explosion, the hospital was astir with overworked nurses and doctors.
・Vocabulary.com: Someone who's astir is awake and moving around. When you check on a sleeping baby, you can describe her as astir if she's up and crawling in her crib.
If your family wakes up early in the morning, you can say they're astir before the sun comes up — or your dog might always be the first one astir each day. You can also use the adjective astir to describe an excited kind of movement: "The whole classroom was astir after the news of tomorrow's pizza party." The earlier phrase was on the stir, from the Old English styrian, "to stir, agitate, or incite."

接頭辞の 'a' は "afloat"、"alive"、"asleep" の様に "the condition or state of" として働いているのですね。