Firefighters aren't empowered to rescind your civil liberties. And they're not armed.

They absolutely are empowered to abridge your civil liberties. Firefighters can break into your home, smash out the windows, cut holes in the roof and leave you with the bill without ever asking your permission. Not to mention what they can do to your vehicle it happens to be in the way of their engines. Then they and the city can prevent you from re-entering your home until they consider it safe.

They only have that power when there's an actual emergency, such as a fire. That doesn't happen too often.

Also, whatever power they do have, they don't seem to abuse, because no one ever complains about the firefighters abusing power.

They have the power to declare the emergency, or in Carl Schmitt's terms, the state of exception.

Interesting point. Firefighters don't carry guns, so they can't literally shoot you, but they can probably take your property and run over your dog with just as much impunity as police.

So why is it the police are the only ones who are known for taking your property and killing your dog? Maybe the property-takers and dog-killers are naturally drawn to that profession more?