Sustained winds of more than 100mph have caused landslides, ripped off roofs and brought down trees in the Philippines as Typhoon Mangkhut pummeled northern areas of the country.
Two rescue workers were killed as they tried to free people trapped in the mountainous Cordillera region, Ricardo Jalad, head of the nation’s disaster agency said.
A body was also found in a river in Manila, police said.
In neighbouring Taiwan, a woman died after being swept out to sea.
The storm, with gusts reaching 190mph, knocked out power as it tore across the northern part of Luzon island – an area that is home to around 10 million people, many of whom live in flimsy wooden homes.
More than 100,000 evacuees took refuge in emergency shelters following a mass evacuation of coastal areas.
There are storm warnings in 10 northern provinces.
“We believe there has been a lot of damage,” social welfare secretary Virginia Orogo said.
Defence Secretary Delfin Lorenzana said officials were verifying whether two children had drowned in northeastern Cagayan province.
“It’s still a life and death situation,” he said.
Mr Lorenzana added that Tuguegarao airport’s terminal roof and windows had been shattered, with the wind flipping chairs and tables around inside.
It is the start of the rice and corn harvesting season in Cagayan province, where farmers have been scrambling to save what they can of their crops.
The Philippines is no stranger to severe weather, where there are an average of 20 typhoons and storms each year.
Mangkhut is the 15th – and the strongest – storm this year.
It is heading towards Hong Kong, where Security Minister John Lee Ka-chiu warned residents it would be bringing “winds and rains of extraordinary speeds, scope and severity”.
He added: “Each department must have a sense of crisis, make a comprehensive assessment and plan, and prepare for the worst.”
Airline Cathay Pacific said it expected more than 400 flight cancellations over the next three days.