A 12-year-old girl caught in the crossfire was among the dead in the town of Kalibo on the island of Panay, which has aviation links to Manila and is a transit point for Boracay.

Police officer Jonathan Moreno was in a security detail that had accompanied Aklan provincial police chief Senior Superintendent Odelardo Magayanes to mass at Kalibo Cathedral, along with fellow security aides, senior police officer Juan Gorion and police officer David Tombong.

In the streets outside, the wild fiesta of Ati-Atihan - in celebration of Santo Nino or the infant Jesus - was in full swing.

On the way back to the police station about 8am, Moreno fell two steps behind, dropped on one knee and repeatedly shot Magayanes and his two fellow officers in the back with an M-16 assault rifle. Tombong had been due to get married on February 14.

The shooting began just as drum rolls and shouts of 'Viva' rang through the plaza of the town. A fireworks display initially masked the sound of gunshots.

As soon as the gunfight became evident, hundreds of revellers scrambled for safety.

Also killed were Kalibo town police chief Manuel Ilejay Jnr and Police officer Ricky Orquiola - both had tried to respond to the shooting.

The sixth victim was a 12-year-old girl, Jodelyn Cuales.

While fleeing, Moreno waved at fellow officers before shooting at them. They fired back and killed him. At least 47 spent M-16 shells were recovered from the scene.

'It was just one policeman that ran amok,' Tourism Secretary Joseph Ace Durano said.

Quoting a briefing from national police chief Edgardo Aglipay, Mr Durano added: 'For some reason this policeman had been having personal problems.'

The Ati-Atihan is the nation's religious version of the mardi gras in honour of the child Jesus - participants dance to the beat of tom-toms with soot-blackened faces, while wearing colourful masks and headdresses.

The festival in Kalibo attracts tourists from all over the world, but the local radio station said there were no reports of foreigners being among the injured.

Ironically, Magayanes and his three aides were in Kalibo to provide additional security for the week-long festival, attended by thousands of foreign and local tourists every year.

Mr Aglipay said Moreno had evidently suffered from a 'psychological imbalance'.

Fellow officers said he had been noticeably silent over the past few days.

Moreno was recently reassigned out of Boracay after he hit someone with a boat paddle. He also served as star witness after a large drug bust and was believed to have received threats against his family from a narcotics kingpin.