A woman who died in a Belmont Shore fire appears to have been smoking and using oxygen when the blaze sparked in her apartment late Monday night, according to authorities.

Fire investigators have determined the blaze began accidentally. They said the oxygen use and smoking likely contributed to starting the flames. Coroner’s officials identified the woman as 61-year-old Karen Tobin.

Authorities also released more details Wednesday about how Tobin’s husband tried to save her after the flames broke out around 11:30 p.m. at their shorefront apartment on 38th Place near East Ocean Boulevard.

The husband was asleep upstairs in the couple’s split-level unit when an alarm on Tobin’s oxygen apparatus alerted him something was wrong, LBFD spokesman Jake Heflin said.

He went downstairs to try to put out the blaze, but he couldn’t, according to Heflin. He said the man then tried to get her out of the home but failed.

Tobin was bedridden and used a motorized chair to get up and down the stairs, according to Heflin. The husband is also in his 60s according to a neighbor.

The husband got out, and when firefighters arrived, he told them his wife was still trapped inside, according to authorities.

Neighbor Chuck Schumacher said he watched crews pull her out, but it was too late. Rescuers rushed her to the hospital where she died, Heflin said.

The husband was hospitalized with moderate injuries, authorities said.

Editor’s note: This story was updated with Tobin’s name Friday morning.

City News Service contributed to this report.