GILROY -- A Fresno couple and two children were killed when a single-engine plane crashed and burst into flames in the rugged hills of southern Santa Clara County, authorities said Saturday.

The two adult victims were identified as Matthew Armstrong, 41, and Sara Armstrong, 37, according to the Santa Clara County Medical Examiner-Coroner's office. Coroner Investigator Rosa Rodriguez said autopsies on the four victims have been completed, but the official causes and times of death would not be publicly released.

The coroner's office would not release the names of the two children killed. But family members told The Fresno Bee that the Armstrongs' niece, 11-year-od Kacie Kusalich, and their soon-to-be-adopted son, 4-year-old Cody, died when the Cessna 172 plane crashed in a remote area southeast of the Coyote Lake reservoir on Wednesday night.

Family members said the Armstrongs and their two teenage daughters had moved from Los Banos to Fresno earlier this year after Matthew Armstrong decided to relocate his machine parts business from Gilroy.

The two daughters will live with their uncle, Nathan Kusalich of Fresno, whose daughter Kacie died in the crash, said Helen Espy, Sara Armstrong's mother.

"Every Christmas there is going to be this memory," Espy said. "But we all believe that they are happy looking down on us and they are in a better place. It's just that we miss them so dearly."

A memorial service is planned at Fresno's Northside Christian Church.

On Friday afternoon, two people were killed when another small plane traveling from Santa Barbara crashed in the hills east of Livermore.

The single-engine Beechcraft 36 Bonanza was attempting to land when it crashed about seven miles east of Livermore Municipal Airport around 3:20 p.m., according to the Federal Aviation Administration.

The National Transportation Safety Board was leading the investigation into the cause of the crash. The identities of the victims have not been released.