Two people died and two others were injured in California after an 86-year-old woman using an oxygen lit a cigarette, causing an explosion.

Los Angeles County firefighters responded to a call of a house fire in Altadena after 10 p.m., where they found the home on Hollison Avenue engulfed in flames, according to a KABC report.

A wheelchair-bound 58-year-old man and his bedridden 86-year-old mother were killed in the ensuing fire, authorities said.

The explosion was so loud that neighbors thought they heard an earthquake. Residents in a two-story house nearby felt the building shake violently.

Authorities said that the elderly woman was using an oxygen tank and was smoking a cigarette, which likely caused the blaze. The fire was suppressed a few minutes after firefighters arrived.

There were two other people inside the home who had to be hospitalized due to the fire, and their condition is currently not known.

The man and his mother had apparently been living together for the past 30 years, and authorities are currently investigating the fire fully.

Altadena is an unincorporated area on the very northern edge of the Los Angeles metropolitan area, about 14 miles from downtown Los Anelges and direclty north of Pasadena. Its population was 42,777 as of 2010.