At least 12 people have died after Typhoon Mangkhut caused landslides, ripped off roofs and brought down trees in the Philippines.

An infant and another child were among four people killed in a landslide in the province of Nueva Vizcaya, while many others were injured.

Presidential adviser Francis Tolentino said about 87,000 people had been evacuated from high-risk areas, while there were storm warnings in 10 northern provinces.

The typhoon, with gusts reaching 190mph, knocked out power as it tore across the northern part of Luzon island - an area that is home to about 10 million people, many of whom live in flimsy wooden dwellings.

Typhoon Mangkhut strikes Philippines

Defence Secretary Delfin Lorenzana said Tuguegarao Airport's terminal roof and windows had been shattered, with the wind flipping chairs and tables around inside.


"We believe there has been a lot of damage," social welfare secretary Virginia Orogo said.

Two air force cargo planes and 10 helicopters were on standby in Manila to help transport rescuers and aid supplies.

:: 'Terrifying and horrible': Houses knocked sideways in Philippines by Typhoon Mangkhut

Image: A damaged house in Pangasinan province

While the state weather agency PAGASA downgraded the threat level, it also said storm surges and heavy rain could still cause widespread flooding and landslides.

"We are asking the people to remain alert and continue taking precautions," said meteorologist Rene Paciente.

Image: Tuguegarao Airport was badly damaged by the storm

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 - it sees an average of 20 typhoons and storms each year.

Mangkhut is the 15th - and the strongest - storm of 2018.

Image: Strong waves in Manila brought by Typhoon Mangkhut

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."

Cathay Pacific airline said it expected more than 400 flight cancellations over the next three days.