The death toll from a typhoon in the northern Philippines has risen to six, official figures showed Thursday, as the storm swept towards southeastern China.

Typhoon Doksuri battered the main island of Luzon on Wednesday, toppling trees, knocking out power and forcing the evacuation of thousands of people from coastal communities.

Strong winds and heavy rain pummelled the lightly populated Babuyan islands and northern provinces, triggering flooding and landslides.

A mother and her three children were killed Wednesday morning when a landslide struck their house in Buguias municipality in the mountainous province of Benguet, local disaster official Satur Payangdo told AFP.

Five other people in the house were rescued.

That took the death toll to six, after a woman was killed by a falling coconut tree in Isabela province and a 16-year-old boy was crushed to death by a landslide in Baguio city.

Doksuri had been a super typhoon as it swept across the Pacific Ocean on Tuesday but weakened as it neared the Philippines.

The storm is expected to weaken further as it moves across the South China Sea before making landfall in southeast China on Friday.

While Doksuri will bypass Taiwan, heavy rains related to the typhoon led to the drowning death of a 57-year-old woman who was trapped with two others when a mountain river overflowed, the island's emergency operations centre said.

The rains also caused power outages in around 43,000 households, though most have been restored.