They were caught flat-footed by the attack.

他们冷不防遭到了攻击。

《牛津词典》

This prisoner was trying to escape but was caught flat-footed in attempt.

有两个囚犯企图逃走，但就在逃跑当中被抓获了。

youdao

This prisoner was trying to escape but was caught flat-footed in attempt.

有两个囚犯企图逃走，但就在逃跑当中被抓获了。

youdao