Prosecutor Michaela Schnell of the Sankt-Poelten office said the inquiry concerns two organisers of the event, which took place at Poechlarn castle on Saturday.

Fierce gusts of wind wrenched off the hefty branches of a centuries-old maple tree, which crashed down onto tents put up for the Middle Ages festival, crushing and trapping participants.

Two people were killed and 11 were seriously injured.

An expert has been appointed to inspect the state of trees in the grounds of the castle after the branches were torn off.

A 51-year-old man died on Saturday night and his eight-year-old son suffered from concussion. A second man, aged 32, died of his injuries late Monday.

The Poechlarn park is currently closed to the public.

Heavy downpours battered parts of the country for the third day in a row, forcing the evacuation of more than 145,000 people, said civil defence chief Benito Ramos.

"It will take about four or five days for the waters to recede, assuming the rains stop now. But if it continues to rain, then naturally, these floodwaters will get even higher," he told AFP.

He warned that the bad weather would last for at least two more days as the floods rose in coastal areas just outside Manila.

Schools in some suburban Manila areas and in nearby provinces remained suspended Tuesday, but workers were forced to wade in floods as they struggled to report for work, officials said.

Three more people drowned, another was killed by a falling tree while a fifth was electrocuted while crossing a submerged bridge, adding to the three deaths reported on Monday, Ramos said.

Rescuers were also searching for four fishermen still missing after two days at sea, he added.

Typhoon Saola has slowed down as it moved away, prolonging its effects over the northern portions of the archipelago, said Ramos.

Saola has dumped heavy rains across large parts of the Philippines since Sunday, causing floods and knocking out power lines to more than two million households, officials said.

Power was restored a day later, but some roads and bridges had remained cut off.

Although Saola did not directly hit the Philippines, its massive rain band exacerbated the effects of a low pressure area in the vicinity.

Saola was heading slowly northward to Taiwan, packing maximum sustained winds of 120 kilometres (74 miles) an hour near its centre, state weather bureau said.

About 20 storms slam into the Philippines from the Pacific every year, causing heavy casualties and damage.