This is the 15045th most frequent Russian word.
пожарных
"Пожарных" means "firefighters" in English.
In this sentence, 'пожарных' is used as a possessive noun, indicating the truck belonging to the firefighters.
Машина пожарных быстро прибыла на место происшествия.
The firefighters' truck quickly arrived at the scene of the incident.
Here, 'пожарных' refers to the firefighters themselves, in the genitive case after the word 'группа'.
Группа пожарных тренировалась на специальном полигоне.
A group of firefighters trained at a special ground.
In this example, 'пожарных' describes the service consisting of firefighters, used in a possessive context.