a fight, often unexpected, between opposing groups of soldiers in which they shoot at each other

The opposing units opened fire simultaneously at close range and a 15-minute firefight ensued. 交战的部队在近距离内同时朝对方开火，交火持续了15分钟。

to spend time on problems that need to be dealt with quickly, instead of working in a calm, planned way

Will the new manager be able to do anything other than firefight? 新的经理除了火急火燎之外还能做点什么？