A woman died in a fire at an oceanfront apartment building in the Belmont Shore neighborhood of Long Beach on Monday and her husband—who tried to save her—was hospitalized, authorities said.

Firefighters responded around 11:30 p.m. to an apartment complex on 38th Place near East Ocean Boulevard after getting reports about an explosion, according to the Long Beach Fire Department. When they arrived, they found heavy smoke and fire coming from a split-level unit, LBFD spokesman Jake Heflin said.

“I couldn’t even see the building through the smoke,” said neighbor Chuck Schumacher who watched the commotion from his porch overlooking the blaze.

Dozens of firefighters swarmed the building, some of them clamoring onto the roof to cut a hole. Just as they completed their job, flames shot up all around them, according to Schumacher.

Outside, the husband told firefighters his wife was still trapped in the apartment, according to Heflin.

Woman killed in fire was smoking, using oxygen when flames began, LBFD says

A few moments later, Schumacher watched as rescue crews pulled something out of the home. He later learned it was his neighbor.

“I thought they just had a bundle of clothes,” he said.

Firefighters found her at the bottom of a stairway inside the apartment, according to Heflin. He said the wife apparently had some mobility issues and used a motorized chair to get up and down the staircase.

“The husband apparently had gotten himself out and had tried to assist his wife out but was unable to do so,” Heflin said.

Heflin said crews immediately took the woman to the hospital, but she didn’t survive.

Schumacher said the couple has lived at the apartment building for many years. They’re in their 60s. He said they were always pleasant and neighborly.

“They’re just very sociable,” he said.

After the blaze died down, Schumacher said he saw the husband wave to a group of nearby neighbors or friends as he climbed into an ambulance. Rescuers took him to the hospital as well to treat moderate injuries, Heflin said.

The cause of the fire was under investigation. Heflin said it’s not clear yet if the blaze was started by some kind of explosion.