LOS ANGELES - SIXTEEN children were left orphaned in the Christmas Eve massacre carried out by a gunman dressed as Santa Claus who slaughtered his ex-wife and her family, it was reported on Saturday.

Authorities have yet to formally identify the nine people killed by Bruce Pardo, 45, who opened fire at the home of his former in-laws on Wednesday before setting fire to the house and later taking his own life.

But the devastating impact upon the family of his ex-wife - identified in media reports as Ms Sylvia Ortega - has slowly begun to emerge as grief-stricken friends and associates speak out in the aftermath of the tragedy.

Pardo's rampage is reported to have claimed the lives of his ex-wife, her parents, her two brothers and their partners, and another relative Alice Ortiz and her teenage son.

Ms Sylvia Ortega's three children were at the party but survived, Scott Nord, the family's lawyer, told NBC4 television. 'The entire family was wiped out,' Mr Nord said. 'There's basically like 16 orphans.'

Three people injured in the assault but are expected to survive. They include an eight-year-old girl who was shot in the face after excitedly opening the door of the home to Pardo because she wanted to see Father Christmas, police told reporters on Friday.

No additional victims are expected to be discovered in the charred wreckage of the Ortega's home, which is to bulldozed, police said.

Family lawyer Nord meanwhile told NBC4 that contrary to reports, Pardo's recent divorce from Ms Ortega - cited as a possible trigger for the attack - had not been especially acrimonious.

He said there were 'no theatrics in the courtroom, no theatrics in the hallway,' Mr Nord said. 'Everybody was very civil to each other.' 'There was no history of domestic violence in this case or none that my client had ever told me about,' he said, admitting he was at a loss to explain what may have pushed Pardo over the edge.

'I can't even give you a rationale,' Mr Nord said. 'I've never seen anything like this happen. I've never even heard of anything like this happening.'

Meanwhile, the Los Angeles Times reported on Saturday that Pardo's marriage had been strained after Ms Ortega discovered he had a brain-damaged son from a previous relationship that he had kept secret.

According to the Times, citing a source close to the police investigation, Ms Ortega was appalled that Pardo had abandoned his child yet continued to claim him as a tax write-off.

Police revealed on Friday that Pardo had planned to flee to Canada following his attack, but killed himself after being seriously injured as he set fire to his former in-laws' home with a home-made flamethrower that melted his Santa Claus costume to parts of his body.

Pardo shot himself after driving to his brother's home. Covina police said 17,000 dollars (S$24,600) was found taped to his body along with a plane ticket to Canada departing early on Thursday.

He had also booby-trapped his car, which burst into flames as bomb disposal experts moved in, police revealed. -- AFP