Stinging from an acrimonious divorce, a man plotting revenge against his ex-wife dressed up like Santa, went to his former in-laws' Christmas Eve party and slaughtered at least six people before killing himself hours later.
Three people were listed as missing after Bruce Pardo's rampage - his ex-wife and her parents - and it was feared their remains were among the ashes of the home, which Pardo set ablaze using a bizarre homemade device that sprayed flammable liquid.
Pardo, 45, had no criminal record and no history of violence, according to police, but he was angry following last week's settlement of his divorce after a marriage that lasted barely a year.
"It was not an amicable divorce," police Lt. Pat Buchanan said.
Pardo chose to exact his revenge at the annual Christmas party his former in-laws held at their two-story home on a cul-de-sac in a quiet Covina neighborhood 25 miles east of Los Angeles.
In past years, a neighbor dressed as Santa Claus and entertained guests.
But the neighbor had moved away and there was no Santa - until Pardo arrived about 11:30 p.m.
The massacre began when an 8-year-old girl answered Pardo's knock at the door.
Pardo, carrying what appeared to be a large present, pulled out a handgun and shot her in the face, then began shooting indiscriminately as about 25 partygoers tried to flee, police said.
A 16-year-old girl was shot in the back, and a 20-year-old woman broke her ankle when she escaped by jumping from a second-story window.
Those two, and the 8-year-old, remained hospitalized Christmas Day.
All were expected to recover.
The gift-wrapped box Pardo was carrying actually contained a pressurized homemade device he used to spray a liquid that quickly sent the house up in flames.
Police said Pardo had recently worked is the aerospace industry.
David Salgado, a neighbor, said he saw the 8-year-old victim being escorted to an ambulance by four SWAT team members as flames up to 40 feet high consumed the house.
"It was really ugly," Salgado said.
Another neighbor, Jan Gregory, said she saw a teenage boy flee the home, screaming, "'They shot my family.'"
When the fire was extinguished early Thursday, officers found three charred bodies in the living room area.
"They were met with a scene that was just indescribable," police Chief Kim Raney said.
Investigators found three more bodies amid the ashes later in the day.
None of the dead or missing have been identified.
Authorities were unable to immediately determine whether the victims were killed by the flames or the gunfire.
Following the shootings, Pardo quickly got out of the Santa suit and drove off, witnesses told police.
He went to his brother's home about 25 miles away in the Sylmar area of Los Angeles.
No one was home, so Pardo let himself in, police said.
Police were called to the home early Thursday, and officers found Pardo dead of a single bullet to the head.
Two handguns were found at the scene, and two more were discovered in the wreckage of his former in-laws' house.