Santiago, Isabela province, the Philippines (CNN) Super Typhoon Mangkhut slammed into the Philippines in the early hours of Saturday, bringing ferocious gale-force winds and pounding rains, as aid agencies warned millions are at risk from rising flood waters and landslides.

Mangkhut was the strongest storm anywhere on the planet in 2018, carrying gusts of up to 325 kilometers per hour (200 mph) before it made landfall in Cagayan province, on the northern tip of Luzon, about 1:40 a.m. local time.

When it crossed land, Mangkhut was packing winds of up to 270 kph (165 mph), 120 kph (75 mph) stronger than Hurricane Florence that hit North Carolina on the same day.

After the center of the storm passed the Philippines, Mangkhut's winds slowed enough for the typhoon to lose its "super" status, but it remains a very powerful storm system with maximum sustained winds of 215 kph (134 mph), equivalent to a category 4 hurricane.

It's now pounding the Philippines with heavy rain, and heading west into the South China Sea toward Hong Kong and southern China.

Sailors remove debris on a US naval base in Guam on Tuesday, September 11, after the typhoon swept through the island territory , causing flooding and power outages.

High-rises are visible above choppy waters in Hong Kong's Wan Chai District on Wednesday, September 12.

High-rises are visible above choppy waters in Hong Kong's Wan Chai District on Wednesday, September 12.

Duterte, second from left, observes the disaster agency's operation center in action in Manila on September 13.

Duterte, second from left, observes the disaster agency's operation center in action in Manila on September 13.

Philippine President Rodrigo Duterte arrives for a government briefing on the typhoon at the National Disaster Risk Reduction and Management Council in Quezon City on Thursday, September 13.

Philippine President Rodrigo Duterte arrives for a government briefing on the typhoon at the National Disaster Risk Reduction and Management Council in Quezon City on Thursday, September 13.

A worker steps over sandbags ahead of the typhoon's arrival in Hong Kong on September 14.

A worker steps over sandbags ahead of the typhoon's arrival in Hong Kong on September 14.

People secure the roof of a house in Tuguegarao on September 14.

People secure the roof of a house in Tuguegarao on September 14.

Workers lay sandbags at the waterfront of the Lei Yue Mun area of Hong Kong on September 14.

Workers lay sandbags at the waterfront of the Lei Yue Mun area of Hong Kong on September 14.

Residential buildings in Hong Kong are reflected in a McDonald's restaurant window, taped in preparation for Typhoon Mangkhut, on September 14. Hong Kong and Macau are currently in the typhoon's path.

Residential buildings in Hong Kong are reflected in a McDonald's restaurant window, taped in preparation for Typhoon Mangkhut, on September 14. Hong Kong and Macau are currently in the typhoon's path.

A volunteer moves through relief goods September 14 as Tuguegarao prepares for the typhoon's arrival.

A volunteer moves through relief goods September 14 as Tuguegarao prepares for the typhoon's arrival.

An evacuee rests inside an evacuation center in Tuguegarao City on September 14.

An evacuee rests inside an evacuation center in Tuguegarao City on September 14.

Villagers from Aparri cut tree branches on September 14 in preparation for the massive storm.

Villagers from Aparri cut tree branches on September 14 in preparation for the massive storm.

Fishermen secure a boat in Aparri before the storm arrives on September 14.

Fishermen secure a boat in Aparri before the storm arrives on September 14.

A farmer gathers his herd of cows to a safe place as the typhoon nears Tuguegarao City on September 14.

A farmer gathers his herd of cows to a safe place as the typhoon nears Tuguegarao City on September 14.

A satellite image shows the width and trajectory of Mangkhut as it approaches the Philippines on September 14.

A satellite image shows the width and trajectory of Mangkhut as it approaches the Philippines on September 14.

Officials conduct a patrol in Aparri ahead of the typhoon on September 14.

Officials conduct a patrol in Aparri ahead of the typhoon on September 14.

Guests sleep inside a hotel restaurant after strong winds damaged the roof of their room in Tuguegarao City on September 15.

Guests sleep inside a hotel restaurant after strong winds damaged the roof of their room in Tuguegarao City on September 15.

Street sweepers go about their daily business as rain and strong winds pound Manila on September 15.

Street sweepers go about their daily business as rain and strong winds pound Manila on September 15.

Motorists push their motor bikes through a flooded street in Manila on September 15.

Motorists push their motor bikes through a flooded street in Manila on September 15.

Residents make their way through destroyed stalls at a public market in Tuguegarao City on September 15.

Residents make their way through destroyed stalls at a public market in Tuguegarao City on September 15.

A motorist tries to avoid the flooding in Manila on September 15.

A motorist tries to avoid the flooding in Manila on September 15.

Crews work to clear a road of debris in Baggao on September 15.

Crews work to clear a road of debris in Baggao on September 15.

A woman weeps as she describes her family's experiences during the typhoon in Baggao on September 15.

A woman weeps as she describes her family's experiences during the typhoon in Baggao on September 15.

Philippine soldiers help a man with a sick child after fallen electric poles blocked an ambulance transporting them in Baggao, a town north of Manila, on September 15.

Philippine soldiers help a man with a sick child after fallen electric poles blocked an ambulance transporting them in Baggao, a town north of Manila, on September 15.

Members of a family survey their heavily damaged home in Alcala, Philippines, on September 15.

Members of a family survey their heavily damaged home in Alcala, Philippines, on September 15.

An elderly Filipino woman copes in the typhoon-hit town of Aparri, Philippines, on September 15.

An elderly Filipino woman copes in the typhoon-hit town of Aparri, Philippines, on September 15.

A family shares a meal by flashlight inside a temporary evacuation center after electricity was shut off following the onslaught of Typhoon Mangkhut in the city of Tuguegarao, Philippines, on Saturday.

A family shares a meal by flashlight inside a temporary evacuation center after electricity was shut off following the onslaught of Typhoon Mangkhut in the city of Tuguegarao, Philippines, on Saturday.

Volunteers and police check on residents after Typhoon Mangkhut hit Tuguegarao, Philippines, on Saturday.

Volunteers and police check on residents after Typhoon Mangkhut hit Tuguegarao, Philippines, on Saturday.

Fishermen remove their boat from the water ahead of the arrival of Typhoon Mangkhut on the outskirts of Zhanjiang, China, on Saturday.

Fishermen remove their boat from the water ahead of the arrival of Typhoon Mangkhut on the outskirts of Zhanjiang, China, on Saturday.

People pray inside of a temple ahead of the arrival of Typhoon Mangkhut in Sanhe village, China, on Saturday.

People pray inside of a temple ahead of the arrival of Typhoon Mangkhut in Sanhe village, China, on Saturday.

An elderly man waits for a taxi as Typhoon Mangkhut edges closer to Hong Kong, on Sunday, September 16.

An elderly man waits for a taxi as Typhoon Mangkhut edges closer to Hong Kong, on Sunday, September 16.

A wave overwhelms a man as he tries to recover salvageable materials in Manila, Philippines, on Saturday, September 15.

A wave overwhelms a man as he tries to recover salvageable materials in Manila, Philippines, on Saturday, September 15.

Residents stand by a flooded road in Tuguegarao city in northeastern Philippines, on Saturday, September 15.

Residents stand by a flooded road in Tuguegarao city in northeastern Philippines, on Saturday, September 15.

A man takes a photograph as waves crash over a promenade in Hong Kong, on Sunday.

A man takes a photograph as waves crash over a promenade in Hong Kong, on Sunday.

A fire rescue worker helps a child cross a flooded street in the village of Lei Yu Mun in Hong Kong.

A fire rescue worker helps a child cross a flooded street in the village of Lei Yu Mun in Hong Kong.

Workers transfer sacks of grains from a toppled truck in northeastern Philippines on Sunday, September 16.

Workers transfer sacks of grains from a toppled truck in northeastern Philippines on Sunday, September 16.

People battle strong winds as they cross a street in China's Guangdong province on Sunday, September 16.

People battle strong winds as they cross a street in China's Guangdong province on Sunday, September 16.

Villagers look down an alleyway filled with seawater in Lei Yu Mun on Sunday.

Villagers look down an alleyway filled with seawater in Lei Yu Mun on Sunday.

Debris from houses destroyed by Typhoon Mangkhut lay scattered on the ground in Tuguegarao city in northeastern Philippines, on Sunday, September 16.

Debris from houses destroyed by Typhoon Mangkhut lay scattered on the ground in Tuguegarao city in northeastern Philippines, on Sunday, September 16.

Rescue workers help a woman to cross a flooded street in the village of Lei Yu Mun, in Hong Kong on Sunday.

Rescue workers help a woman to cross a flooded street in the village of Lei Yu Mun, in Hong Kong on Sunday.

Rescuers assist a mother and her child after the deadly landslide in the Philippines.

Rescuers assist a mother and her child after the deadly landslide in the Philippines.

Fierce winds and rain pierced this building in Hong Kong. The typhoon tore off roofs, downed trees and caused cranes to swing ominously.

Fierce winds and rain pierced this building in Hong Kong. The typhoon tore off roofs, downed trees and caused cranes to swing ominously.

A taxi is left abandoned after breaking down in Hong Kong.

A taxi is left abandoned after breaking down in Hong Kong.

Rescue workers wade through floodwaters during a rescue operation in Macau on September 16.

Rescue workers wade through floodwaters during a rescue operation in Macau on September 16.

A former school in the Hong Kong village of Shek O was destroyed by Typhoon Mangkhut.

A former school in the Hong Kong village of Shek O was destroyed by Typhoon Mangkhut.

A man holds an umbrella as he walks past fallen trees in Hong Kong on Sunday, September 16.

A man holds an umbrella as he walks past fallen trees in Hong Kong on Sunday, September 16.

Workers in Hong Kong clean up scaffolding that had been knocked down by the storm.

Workers in Hong Kong clean up scaffolding that had been knocked down by the storm.

Rescuers in Itogon continue search operations on Wednesday, September 19. Dozens have been confirmed dead in the landslide, and dozens are still missing.

Rescuers in Itogon continue search operations on Wednesday, September 19. Dozens have been confirmed dead in the landslide, and dozens are still missing.

Evelyn Wigan wipes away a tear as she waits for news of missing relatives who were near the site of a deadly landslide in Itogon, Philippines.

Evelyn Wigan wipes away a tear as she waits for news of missing relatives who were near the site of a deadly landslide in Itogon, Philippines.

A man looks out of a damaged building in Hong Kong after Typhoon Manghkut.

A man looks out of a damaged building in Hong Kong after Typhoon Manghkut.

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 metro Manila once the weather improves, Lorenzana said, carrying aid and allowing rescuers to access 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 told CNN there are no reports of casualties, so far. The biggest immediate issue for emergency services remains clearing debris from main roads, said Maamba. 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.

Tuguerarao airport was damaged as Super Typhoon Mangkhut swept past the Philippines.

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.

Storm chaser James Reynolds, who was in a hotel in Santa Ana, in Cagayan, when the storm hit, described how the winds ripped through the hotel's interior, leaving it uninhabitable.

"There was plywood and shards of glass flying through the corridors," Reynolds told CNN. "It must be hell for the people out there living in huts and fragile homes, must be terrifying."

Many of those in Northern Luzon live in isolated farming communities. There are fears the typhoon could lead to flash flooding in more rural areas, triggering landslides.

Typhoon #OmpongPH at its worst in Tuguegarao City, Cagayan Province as of 12:30 a.m. @cnnphilippines pic.twitter.com/MJ3XRaUM3p — Rex Remitio (@RexRemitio) September 14, 2018

An estimated 5.2 million people in the Philippines were within 125 kilometers (77 miles) of the projected path of the Super Typhoon, according to the National Disaster Risk Reduction and Management Council.

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.

Potential storm surges

Mangkhut is the strongest storm to make landfall in the Philippines since Super Typhoon Haiyan in 2013, which left more than 6,000 people dead , though Haiyan hit a more populated part of the country.

It's also the strongest to make landfall on the Philippines' northern island of Luzon since Super Typhoon Megi in 2010. Northern Luzon was also devastated in 2016 by Super Typhoon Haima, with 14,000 houses destroyed and 50,000 homes damaged, according to CNN Philippines

Before the storm's arrival Friday, parts of Luzon were placed under Tropical Cyclone Warning Signal No. 4 by the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA), meaning those areas could expect winds of up to 185 kilometers per hour (114 mph) that could uproot trees, destroy crops, take out electricity and damage buildings. The agency had warned of storm surges up to 19 feet along the Cagayan and Isabela province coastlines.

At 11:00 a.m. local time, authorities warned of potential storm surges up to six meters high in Ilocos Norte, as Mangkhut moved further off the coast.

As of Friday morning, 2,298 families had been preemptively evacuated from their homes in Ilocos, Cagayan Valley and Cordillera administrative regions in northern Luzon. More than 5,000 people have been evacuated from coastal areas in Isabela province, according to Gov. Bojie Dy.

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.

Officials told CNN Philippines the cost to rice and corn crops could be upward of $116 million, with more than 1,220,000 hectares of fields expected to be damaged by the storm

Southern China braces for impact

Once it passes over the Philippines, Mangkhut will continue west through the Luzon Strait into the South China Sea towards Hong Kong.

As of 1 p.m. local time, the Hong Kong Observatory estimated the typhoon had maximum sustained winds of up to 195 kph (120 mph), equivalent to a Category 3 hurricane. It was 730 kilometers (450 miles) southeast of the city and moving at 30 kph (18.6 mph) towards the coast of western Guangdong.

Mangkhut could be one of the strongest storms to have an impact on Hong Kong in more than six decades. The typhoon will make its closest pass to Hong Kong during the day on Sunday, likely during the afternoon.

Officials in Hong Kong held emergency meetings Friday, and residents in low-lying areas and outlying islands have been urged to move to temporary shelters.

Macau's Meteorological and Geophysical Bureau warned that Manghkut would "pose a serious threat" to the Pearl River Delta, where the city is located.

Last year, 10 people died in Macau as a result of Typhoon Hato, the strongest storm to hit the city in more than five decades. It caused widespread flooding and damage to property.

Typhoon Mangkhut will make another landfall on Sunday night in western Guangdong, China.

Correction: This story has been updated to correct the time Mangkhut made landfall in the Philippines.