Powerful Typhoon Koppu ripped off roofs, tore down trees and unleashed landslides and floods, forcing thousands to flee as it pummelled the northern Philippines.
No casualties were reported on Sunday but more than 9000 people were evacuated from their homes, civil defence officials said, with more expected to leave as the storm grinds inland across the main island of Luzon over the next three days.
Koppu pounded the remote coastal town of Casiguran and nearby areas with gusts up to 210km/h and heavy rain, remaining nearly stationary hours after making landfall there before dawn, the state weather service said.
"It looks likely this deluge will be with us for days," weather forecaster Gladys Saludes said.
The typhoon is likely to leave Luzon, home to half the Asian archipelago's 100 million people, only on Tuesday.
More than 8000 people, or nearly a fourth of the town's population, moved to evacuation centres in Casiguran, about 270km northeast of Manila, according to Nigel Lontoc, the deputy civil defence director for the region.
"Koppu tore off roofs of homes made of light materials," Lontoc said. "Rivers overflowed, and the roads to the area are blocked by downed power pylons and trees."
ABS-CBN network aired footage of a hospital building with its roof ripped off near Baler, the provincial capital that draws surfers from around the world.
Lontoc also said the authorities cancelled a surfing competition in Baler for the weekend and ordered about 2000 participants to remain indoors.
To the west across the Sierra Madre mountain range, nearly 800 other people evacuated in the farming town of Bongabon, he added.
The National Disaster Risk Reduction Council in Manila reported landslides and floods elsewhere in northern Luzon, cutting off roads and bridges.
Its director Alexander Pama told reporters ferry services across the island were suspended amid rough seas while commercial aviation was also disrupted with 30 flights cancelled, two of them on international routes.
"I must emphasise that this is just the start," Pama said. "People must remain alert while we try to pick up the pieces in areas already hit."
Residents of communities in the typhoon's expected path were preparing, said Kate Marshall, part of an advance reconnaissance team of the International Committee of the Red Cross to the region.
"There is a bit of debris around but nothing major as yet," Marshall said from Solano town, about 100 kilometres inland. "The trees are beginning to sway a lot more.
"We have seen people checking roofs and putting stuff away. There are not that many people on the road.... I would say people are prepared," she said, adding local officials have prepared evacuation centres in case they are needed.
Saludes, the weather forecaster, said due to Koppu's unusually slow pace, the mountainous areas and farmlands along river valleys in the area were expected to be lashed by intense rain for days.
This could leave them exposed to floods and landslides, she said.
The weather service has also warned of storm surges, massive typhoon-generated waves smashing along coastal areas, but Saludes said there had been no reports of these so far.
Although the storm will not directly hit Manila, other regions within its 600-kilometre swathe were likely to be affected by strong winds and rain.
The Philippines is hit by an average of 20 storms each year, many of them deadly.
The deadliest and strongest on record, Super Typhoon Haiyan, destroyed entire towns in the central islands in November 2013, leaving more than 7350 people dead or missing.