LOS ANGELES - AT LEAST three people were killed after a gun-toting man dressed as Santa Claus burst into a Christmas Eve party and opened fire before later killing himself, police in Los Angeles said on Thursday.

The body of Bruce Pardo, 45, was found with self-inflicted gunshot wounds early on Thursday, hours after he had launched a murderous assault on a party hosted by a relative of his estranged wife, police said.

Pardo had knocked on the door of the home in a quiet residential neighbourhood in Covina, 23 miles (37 kilometres) east of Los Angeles, just before midnight on Christmas Eve, police lieutenant Pat Buchanan said.

Local media reports said Pardo was let into the house by revelers who thought he had been hired as entertainment for children at the party.

But once inside, he produced a handgun from beneath his costume and opened fire, killing at least three people and injuring three more.

As terrified party-goers fled the scene, Pardo then reportedly torched the house with Molotov cocktails before fleeing.

He was found dead from a single gunshot to the head at his home in Sylmar, approximately 25 miles away, after officers arrived, police said.

Police said more bodies may be found in the charred wreckage of the home.

Lt Buchanan would not confirm reports of further bodies being found but said several of the 30 guests at the party were unaccounted for and 'there is a good possibility that there are other people inside'.

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

Two girls, age 16 and eight, were hospitalised with gunshot wounds and a 13-year-old girl was treated for injuries that were not life threatening.

Around 80 firefighters were deployed to tackle the fire that destroyed the house. Popping sounds - possibly ammunition rounds exploding - were heard throughout the blaze.

After the fire was extinguished, rescuers found three bodies in the basement, Lt Buchanan said, adding Pardo may have been acting on a marital grudge.

'We don't know the exact connection,' Lt Buchanan said. 'But we know Mr Pardo was having some marital difficulties and this residence belonged to a relative of his wife.'

Lt Buchanan told CBS2 television the shooting was 'extremely unusual and very shocking'.

'It's just not something we see here at any time of the year - especially during Christmas,' he said. -- AFP