At work; in the middle of working — used to indicate someone is currently working or within work hours/at the workplace.
今は仕事中なので、後で電話します。
I'm at work now, so I'll call you later.
会議中は携帯をマナーモードにしてください。仕事中に鳴ると困ります。
Please put your phone on silent during the meeting. It's troublesome if it rings while working.
仕事中のミスを防ぐためにチェックリストを使っている。
I use a checklist to prevent mistakes while working.