ELYRIA, Ohio (WJW) — A Thursday morning fire at a Middle Avenue home appears to have been caused by “careless smoking,” fire officials said in a news release.

Elyria Fire Department crews responded just after 9:30 a.m. to the home in the 1700 block of Middle Avenue, where they found a fire that had been mostly extinguished.

Three of the home’s residents were injured: A woman had burns on her foot and two others suffered minor smoke inhalation, according to the release. One of them was taken to a hospital while the other two refused treatment.

The property loss was “minor,” officials said.

“Please be careful when smoking and discarding your ashes and never smoke when you or someone near you is on medical oxygen,” Fire Chief Joseph Pronesti is quoted in the release.

Fire is fueled by oxygen, making lit cigarettes hazardous near someone who’s using medical oxygen. Medical oxygen can saturate clothing, “causing them to ignite and rapidly burn,” according to a report from the Ohio Department of Commerce.

“Even if the oxygen is turned off, residual oxygen levels can cause your clothing and oxygen tubing to catch fire,” reads the report.

There were 137 fire fatalities in 2020. The top cause of all known fatalities was smoking-related, contributing to about one in five fire deaths, according to state fire marshal data.