(CNN) - The extent of the damage inflicted by Typhoon Mangkhut on the northern Philippines was difficult to assess Sunday as fierce winds were replaced by flood waters, blocking access and aid to affected areas.
At least two people were killed as the world's strongest typhoon this year, known locally as Ompong, slammed into the Southeast Asian country in the early hours of Saturday morning.
Mangkhut ripped roofs off buildings, uprooted trees, blocked roads with debris and dumped water on fields of crops that farmers weren't able to harvest ahead of the storm.
The typhoon is closing in on Hong Kong which raised its typhoon warning alert again on Sunday morning local time to T10, the highest level, as the storm swirled 220 kilometers (136 miles) south-southeast of the island.
Mangkhut could be one of the strongest storms to hit Hong Kong in more than six decades, but the city is well prepared for wild weather and started shutting down, closing shops and suspending travel as Mangkut approached.
The storm system is currently moving at 30 kilometers per hour (19 miles per hour) towards the coast of western Guangdong, mainland China, according to the Hong Kong Observatory.
Mangkhut slams into the Philippines
When it made landfall in the Philippines Saturday morning at 1:40 a.m. local time, Mangkhut was packing winds of up to 270 kph (165 mph), 120 kph (75 mph) stronger than Hurricane Florence that hit North Carolina.
While the death toll is likely to rise, there was some relief in the Philippines that it doesn't appear to have been as fatal as other recent, less powerful, storms.
More than 6,000 people died when Super Typhoon Yolanda hit the Philippines five years ago, the worst in a generation. That storm displaced nearly 4 million people. Many of the survivors ran short of food, water and medicine almost immediately.
"Honestly, we were expecting the worst from this," Edgar Posadas, a spokesperson for the National Disaster Risk and Reduction Management Council (NDRRMC) told CNN, of Mangkhut.
"I was praying and hoping and worried about having so much casualties. But I think after Yolanda, after Haiyan [the international name for Yolanda], there were a lot of lessons that were learned in terms of preparedness, early warnings, preemptive evacuations... and this went a long way."
The two people confirmed dead were rescue workers, said Ricardo Jalad, executive director of the Philippines National Disaster Risk Reduction and Management Council. Both victims were women, killed when a rain-drenched hillside collapsed on them, according to the French news agency AFP.
As of Saturday, the storm had caused 51 landslides across the region.
The Philippines military is sending two C-130 airplanes and 10 helicopters to Cagayan province for typhoon relief and rescue efforts, Defense Secretary Delfin Lorenzana said Saturday, according to Philippine News Agency (PNA).
They'll fly from Manila once the weather improves, Lorenzana said, carrying aid and allowing rescuers to reach remote areas of the mountainous north.
Earlier, in the provincial capital Tuguegarao, strong winds lashed buildings, pulling off entire roofs and throwing large chunks of debris into the air.
The Governor of Cagayan, Manuel Maamba said emergency services are clearing debris from main roads. Power and communication lines are also down, making it hard to contact more remote areas and assess damage.
Tuguegarao airport in northern Luzon, a vital transportation hub, has also been damaged, potentially complicating efforts to bring in humanitarian aid.
The Philippines Red Cross said waters were rising in parts of Tuguegarao. Video on social media showed people in the city wading through ankle-deep water, amid torrential rains.
"There was plywood and shards of glass flying through the corridors," storm chaser James Reynolds, who was in a hotel in Santa Ana, in Cagayan, told CNN. "It must be hell for the people out there living in huts and fragile homes, must be terrifying."
The scale of the typhoon could be felt in the Philippines capital Manila, more than 340 km (200 miles) from the eye of the storm, where heavy overnight rains have led to widespread flooding in urban areas.
Heading to China
Mangkhut's eye is now over water in the South China Sea and making its way toward Hong Kong and southern China. The Hong Kong Observatory urged the public to stay on the alert and said the typhoon will be closest around noon Sunday.
Residents taped up windows and secured anything that could take flight in strong winds.
Strong winds and heavy rain hit Hong Kong during the early hours of Sunday, and conditions are expected to intensify as the day goes on. Current sustained winds are at 165 kph (102 mph) with wind gusts of up to 205 kph (127 mph), according to the Hong Kong Observatory.
Wind gusts of over 100 kph (62 mph) have already been recorded at a number of locations in the city, according to CNN's Weather Unit, which predicts wind speeds will increase in the coming hours.
Flights from Hong Kong International Airport were delayed or canceled Sunday, disrupting the travel plans of thousands of passengers. Travelers were urged to check with their airlines.
Train, bus and ferry services to the airport were also suspended, though the airport remains open for passengers who have nowhere else to go.
Typhoon Mangkhut will make another landfall on Sunday night in the Chinese province of Guandong near the cities of Yangjiang and Zhanjiang.
From there the system will continue to move westward and will rain itself out over northern Vietnam, which could lead to some flooding there early next week.
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