LOS ANGELES - A NINTH body was recovered from the charred rubble of a Christmas Eve massacre on Friday as sketchy details emerged about the gunman responsible for the deadly killing spree.

Los Angeles County Coroner's office confirmed a ninth body had been found in the wreckage of a home in the eastern suburb of Covina, where a man dressed as Santa Claus opened fire on revellers late on Wednesday.

The gunman, Bruce Pardo, 45, burst into the party at his former in-laws home and sprayed guests with bullets before setting fire to the house and later taking his own life.

Pardo had recently gone through a bitter divorce with his wife - who was reported to be among the victims - but there were no further clues as to what may have triggered the murderous rampage.

The unemployed aerospace engineer had no criminal record and nothing in his personal history to suggest a predisposition to violence, police said. Friends from a church Pardo attended regularly expressed disbelief.

'He was just the nicest guy,' said Ms Jan Detanna, who worked with Pardo as an usher at the Holy Redeemer Catholic Church.

'He always had a smile. It's a shock. A shock for anybody who knew him at the church,' Ms Detanna told the Whittier Daily News.

Grief-stricken friends of the victims on Thursday described Pardo as a 'coward'. 'To know that one individual, one coward, could bring so much devastation and heartache to a family,' said family friend Rosa Ordaz.

Police said Pardo knocked on the door of his ex-wife's parents' home just before midnight, where 25 people were gathered to celebrate Christmas Eve.

An eight-year-old girl who answered the door was shot in the face before Pardo stormed into the home and began gunning down revelers with bullets fired from a semi-automatic handgun.

After party-goers fled, Pardo torched the house with a bizarre home-made incendiary device before making his getaway.

Pardo's body was found with self-inflicted gunshot wounds early on Thursday, a few hours after the rampage, police said. He had been killed by a single shot to the head at his brother's home in Sylmar, approximately 25 miles away.

Late on Thursday, a rented car parked outside the property was discovered to be loaded with 300 rounds of ammunition and a pipe bomb. The car burst into flames as bomb disposal experts moved in, reports said.

Police had received a series of emergency calls alerting them to the initial incident, and when they arrived, the house was engulfed in flames and guests were running out, Buchanan said.

Neighbours reported hearing a loud explosion before the blaze erupted.

Two girls, including the girl who answered the door, were hospitalised with gunshot wounds and a 13-year-old girl was treated for injuries that were not life-threatening.

Authorities have yet to publicly identify those killed by Pardo, but local media reported the victim's ex-wife and in-laws were among the dead.

It was not clear if three people at the party who were missing on Thursday had been accounted for. -- AFP