The man was dressed as Santa Claus when he knocked on the door of a well-to-do house in Covina, California, just before 11.30pm on Christmas Eve. A party with about two dozen guests was going on inside.

From the doorstep, he could hear laughter, glasses clinking, Christmas music playing. A girl aged 8 heard the knocking and ran up the hallway to see who was there. No doubt she was surprised and delighted to see Father Christmas, holding what looked like a large, wrapped present.

That was when Santa shot her in the face at almost point-blank range with a semi-automatic handgun before pushing his way into the house and turning his weapon indiscriminately on the other party guests. He then incinerated them with a homemade form of napalm.

Screaming guests dived for cover or tried to flee the furnace of the living room. One girl leapt from a second-floor window, breaking her ankle when she smashed into the concrete below. Jan Gregory, a neighbour, said she saw a teenage boy run from the house screaming: “They shot my family.”

Astonishingly, the eight-year-old girl survived, as did another aged 16 who was shot in the back.

But at least nine others perished in the worst mass shooting this year in the United States and possibly the most horrific domestic attack in California since associates of Charles Manson repeatedly stabbed the pregnant model Sharon Tate to death at her Beverly Hills home in 1969.

The killer was identified yesterday as Bruce Jeffrey Pardo, and the house he attacked belonged to his former inlaws, Joseph Ortega, 80, and Alicia Ortega, 70. It is believed that they died in the gunfire, along with Pardo’s former wife Sylvia, 43.

The couple’s acrimonious divorce had been finalised last week, and under its terms Pardo had been ordered to hand over $10,000 and the family dog.

Pardo had lost his job at ITT Electronic Systems, a military defence supplier, in July and was “desperately seeking” work. He had complained that his wife, who filed for divorce in March, was living with her parents, not paying rent, while he struggled to pay support.

Last night police said that Pardo had been planning to flee but had killed himself instead after his Santa suit melted onto his body. He was discovered dead with $17,000 and an aeroplane ticket to Canada, they told a press conference.

Emergency crews were still trawling the blackened wreckage of the house yesterday, having worked at the crime scene throughout Christmas Day.

“We have multiple bodies inside,” said Ed Winter, of the Los Angeles Coroner’s Office. “They’re extremely charred and burnt.”

The body of Pardo – who had volunteered to serve as an usher at Midnight Mass at the Holy Redeemer Catholic Church in his home town of Montrose before deciding instead to put on a Santa suit and drive a rental car to the home of his former inlaws – was discovered on Thursday at his brother’s house in Slymar, about 40 miles away from the Ortegas’ property. He had died of a single gunshot wound to the head. Police said that a pipe bomb exploded early yesterday in the hire car parked outside his brother’s home.

Friends of the Ortegas yesterday expressed their shock at the slaughter. “To know that one individual, one coward, could bring so much devastation and heartache to a family,” said Rosa Ordaz.

Police said that they received several emergency calls regarding gunshots fired in Covina at 11.30pm on Christmas Eve and were still hearing the gunshots after they arrived and found the house in flames. At first, firefighters were told not to approach the property because of the gunfire, although it was probably burning ammunition. The flames were finally put out at about 1.30am on Christmas Day.

Neighbours remained in shock yesterday. “This neighbourhood is really quiet,” said Jeffrey Barrientos, who lives half a block from the Ortegas’ house. At Pardo’s homepolice found a wreath hung on the front door and children’s sweets hanging from the fence. An SUV and a military-style Hummer were parked in the driveway. After searching the property, detectives said it appeared that the shooting and the napalm attack had been planned.

They said that his ability to construct a homemade napalm gun had probably been a result of his training in the aerospace industry.

When told of the killings, friends of Pardo struggled to believe what had taken place.

“Bruce?” said Jan Detanna, the head usher at his church. “He was the nicest guy you could imagine. Always a pleasure to talk to, always a big smile.”

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