Witnesses say the storm's wind and rain ripped off tin roof sheets, and knocked out power in some places.
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 4 million people live in areas at most risk from the storm, which the Joint Typhoon Warning Center in Hawaii categorized as a super typhoon with powerful winds and gusts equivalent to a category 5 Atlantic hurricane.
"Almost all of the buildings here have been damaged, the roofs were blown away", Rogelio Sending, a government official in Tuguegarao, the capital of Cagayan, told Reuters.
The storm's massive raincloud band is 900 kilometers (560 miles) wide.
Cagayan Governor Manuel Mamba said he expects widespread damage to crops and infrastructure in his province, and said help would be needed to rebuild.
Those who live in the typhoon's projected path and can not flee have been reinforcing their homes and stocking up on food. It was not immediately clear whether the deaths and missing cited by Domogan had been included in Tolentino's count.
A super typhoon wrought heavy damage to Banez's hotel and the rest of Cagayan in 2016.
According to GDACS, the storm formed over the northwestern Pacific Ocean last Friday and strengthened as it moved past the Mariana Islands and the United States territory of Guam.
ASSOCIATED PRESS A convenience store is taped in preparation for approaching Typhoon Mangkhut in Hong Kong on Saturday
Cheng said the Hong Kong Observatory might issue a typhoon signal No 8 at "a relatively early time" on Sunday which may be followed by a signal No 9 or 10, depending on the storm's proximity to the city and its wind strength.
"If we didn't, all of us would be dead", Abedes said.
There are unconfirmed reports of casualties in the coastal town of Aparri, where the evacuation centre is said to have been destroyed and phone networks are down. According to Agriculture Secretary Emmanuel Piñol, the damage may reduce the country's rice supply and result in losses of up to 7.9 billion Philippine pesos ($146.2 million).
Known locally as Ompong, Typhoon Mangkhut at one point had maximum gusts of 305 kph (190 mph) before it left the Philippines and moved towards Hong Kong and southern China, with wind speeds that reduced to 170 kph (106 mph) then to 160 kph in the evening.
A super typhoon yesterday roared toward the Philippines, prompting thousands to evacuate ahead of its heavy rains and fierce winds that are set to strike at the weekend before moving on to China.
Airlines in Hong Kong have canceled hundreds of flights due to the storm, which is expected to come within 200 km (125 miles) of the city on Sunday and wreak havoc on the Asia financial center and nearby Pearl River Delta.
The gambling enclave of Macau, next door to Hong Kong, suffered catastrophic flooding during Typhoon Hato last August that left 10 dead and led to accusations of corruption and incompetence at its meteorological office.
The Philippines Red Cross said it had activated 30,000 volunteers across Luzon to prepare for the impact of the storm and dispatched a "humanitarian caravan" consisting of rescue and relief vehicles to the parts of the island expected to be among the worst affected. Tens of thousands more have been evacuated from China's Guangdong province, CNN reported.