Smoke detectors are an inexpensive way to protect lives and property.

That fact was emphasized last week during what can be regarded as a careless blaze in the 300 block of Mercer Street.

The three-story home in question houses an apartment on each level. And, according to Butler Fire Chief Nick Ban, the home had no working smoke detectors.

Consequently, rather than the early warning that working detectors could have given to tenants of all of the structure’s apartments, occupants of a second-floor apartment were not made immediately aware that a fire had broken out above them.

They learned about the blaze when the third-floor tenant ran down to their apartment to alert them.

The visitor to the third-floor apartment — the person responsible for the blaze — came running down moments later, yelling, “Just get out!”

The first-floor tenant wasn’t at home when the fire began.

The visitor responsible for the blaze told authorities he had been playing with a cigarette lighter and lying on a sofa smoking in the moments before he noticed that the couch was ablaze.

The downstairs tenants were delayed in learning about the fire because the occupants upstairs tried unsuccessfully to extinguish the flames before exiting the apartment.

Fortunately, the fire didn’t break out when the apartments’ tenants were sleeping. The lack of working fire detectors could have resulted in tragic consequences.

The Mercer Street landlord, who resides in Mercer County, can be faulted for not addressing his basic responsibility of ensuring that his apartments had working detectors on all levels.

For National Fire Prevention Week, which this year was observed Oct. 7 through 13, the American Red Cross, fire departments and firefighter organizations issued reminders about having smoke alarms on every level and inside all bedrooms — and that the batteries of all alarms should be changed once a year and be tested monthly.

Unfortunately, there are other Butler apartment buildings besides the one on Mercer Street where the beep . . . beep . . . of “dying” detector batteries can be heard by those in the building or even nearby outside.

Beyond the landlord’s duty to install detectors, tenants can’t be excused from their responsibility regarding non-working smoke detectors. A battery for a smoke detector costs only a couple of dollars — but the safety value of the batteries is immeasurable.

For the fire in question, Butler firefighters again demonstrated their skills in getting such situations under control quickly. While the flames were contained to the couch, the apartment was damaged extensively by heat from the flames.

The potential for tragedy was increased by the third-floor occupants’ efforts in first trying to extinguish the flames themselves before alerting firefighters.

It’s foolish for homeowners, tenants and landlords — and businesses — to ignore fire-detector reminders when such a low-cost safety asset is available.

Ban estimated damage in the Mercer Street fire at $35,000 — $25,000 to the structure and $10,000 to contents.

The fire should be a reminder to all residents of Butler and surrounding areas.