Couple and Son Killed in Blaze at Arleta House : Emergencies: A neighbor and a passerby rouse the grandparents and help them to safety. But flames and smoke thwart attempts to rescue the others.

A couple and their 3-year-old son died in an Arleta house fire early Saturday, but a neighbor and a passerby were able to rescue the couple’s grandparents from the burning structure before being repelled by smoke and flames, fire officials and witnesses said.

Firefighters were called to the house on Snowden Avenue, south of Osborne Street, shortly after 1:30 a.m. and doused the flames in 20 minutes, Los Angeles Fire Department spokesman Bob Collis said.

George and Jeanette De Motta, a retired couple in their 60s, lived in the house with their 25-year-old granddaughter, her husband and the couple’s son, neighbors said. The younger couple had moved into a room in the back of the house several months ago to care for their ailing grandparents, said neighbors and church friends who gathered at the home after hearing of the tragedy.

The De Mottas were taken to a local hospital for treatment of minor injuries, fire officials said. Jeanette De Motta, who neighbors said is blind, was later released and is staying with friends.

A spokesman for the Los Angeles County coroner’s office said the names of the dead will not be released until Monday or later. But neighbors said the victims were Manuel and Yvette Martinez, both 25, and their son, Nicholas.

The cause of the blaze, which was confined to a rear bedroom, was under investigation.

Carmen Marcial, who lives next door, said she and her husband were alerted to the fire by a man pounding on their front door. The Marcials and the man, who was apparently driving through the neighborhood at the time, tried to warn the De Mottas by pounding on doors and windows, Marcial said.

“Fire was shooting out the back and up into the trees,” Marcial said.

Finally, George De Motta came to a window and was told to open the front door. Marcial’s husband, Osbaldo, then helped him to safety.

The passerby ran inside the house and carried out Jeanette De Motta. He went back inside the house for the others but was driven back by smoke and flames, Marcial said.

The man received oxygen from paramedics, but apparently sustained no injuries, Marcial said.

Someone, Marcial recalled, told the man: “You deserve a medal.”

“All I need is some oxygen,” he replied. Then the man left without giving his name.

Neighbor Andrew Jarvis said he has known the De Mottas since they moved into the neighborhood 20 years ago.

“We’ve been close friends, our children grew up together,” he said. “This is terrible.”