TUGUEGARAO, Philippines — Typhoon Mangkhut lashed the northern Philippines with destructive winds and heavy rain that set off landslides and destroyed homesSaturday, leaving at least 12 people dead, as Hong Kong and other parts of southern China braced for the powerful storm.

The most ferocious typhoon to hit the disaster-prone Philippines this year slammed ashore before dawn in Cagayan province on the northeastern tip of Luzon island, a breadbasket that is also a region of flood-prone rice plains and mountain provinces with a history of deadly landslides.

More than 5 million people were at risk from the storm, which the Hawaii-based Joint Typhoon Warning Center downgraded from a super typhoon. Mangkhut, however, was still punching powerful winds and gusts equivalent to a Category 4 Atlantic hurricane when it hit the Philippines.

China and the Philippines agreed to postpone a visit by Chinese Foreign Minister Wang Yi that was to start Sunday because of the typhoon’s onslaught, which caused nearly 150 flights, a third of them international, to be canceled and halted sea travel.

Francis Tolentino, an adviser to Philippine President Rodrigo Duterte, said the 12 died mostly in landslides and houses that got pummeled by the storm’s fierce winds and rain. Among the fatalities were an infant and a 2-year-old child who died with their parents after the couple refused to immediately evacuate from their high-risk community in a mountain town in Nueva Vizcaya province, Tolentino said.

“They can’t decide for themselves where to go,” he said of the children, expressing frustration that the tragedy was not prevented.

Tolentino, who was assigned by Duterte to help coordinate disaster response, said at least two other people were missing. He said the death toll could climb to at least 16 once other casualty reports were verified.

Mayor Mauricio Domogan said at least three people died and six others were missing in his mountain city of Baguio after strong winds and rain destroyed several houses and set off landslides, which also blocked roads to the popular vacation destination.

Authorities were verifying the drownings of three people, including two children who reportedly died as the typhoon approached. About 70 men reportedly returned to their coastal village in Cagayan to check on their homes as the storm drew closer Friday, but Tolentino said he had received no reports of the men figuring in an accident.

Mangkhut’s sustained winds weakened to 105 mph with gusts of up to 161 mph after it sliced northwestward across Luzon before blowing out to the South China Sea, aiming at Hong Kong and elsewhere in southern China.

About 87,000 people were evacuated from high-risk areas of the Philippines. Tolentino and other officials advised them not to return home until the lingering danger had passed.

“It’s still a life and death situation,” Defense Secretary Delfin Lorenzana said, citing past drownings in swollen rivers in mountain provinces after storms had passed.

Storm warnings remained in effect in 10 northern provinces, including Cagayan, which could still be lashed by devastating winds, forecasters said. Thousands of people in the typhoon’s path had been evacuated.

At daybreak in Cagayan’s capital, Tuguegarao, journalists saw a severely damaged public market, its roof ripped apart and wooden stalls and tarpaulin canopies in disarray. Outside a popular shopping mall, debris was scattered everywhere and government workers cleared roads of fallen trees.

Many stores and houses were damaged but most residents remained indoors as occasional gusts sent small pieces of tin sheets and other debris flying.