Authorities say the incident happened at 6:16 a.m. The 79-year-old woman went to the laundry room to wash her clothes when the room ignited in a small explosion, according to L.A. City Fire spokesman David Ortiz.
Neighbor Consuelo Cooper said the explosion sounded a car slamming into a house, and neighbor Eric Moten said windows and flower pots were blown out.
The woman had burns to over 40 percent of her body. She remains hospitalized in critical but stable condition.
"She was burned pretty bad. It's a gruesome sight," Moten said. "She was in shock. She spoke to us briefly."
Residents in the area said they had smelled gas a couple days ago.
Crews from the Southern California Gas Company responded to investigate. Officials say they've inspected the service line up to the meter of the property and found no leaks.
It remains unclear what caused the explosion.