Philippine authorities were evacuating thousands of people from the path of the most powerful typhoon this year, closing schools, readying bulldozers for landslides and placing rescuers and troops on full alert in the country's north.
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.
Typhoon Mangkhut is on course to hit northeastern Cagayan province early Saturday. It was tracked on Friday about 400 kilometers (250 miles) away in the Pacific with sustained winds of 205 kilometers (127 miles) per hour and gusts of up to 255 kph (158 mph), Philippine forecasters said.
With a massive raincloud band 900 kilometers (560 miles) wide, combined with seasonal monsoon rains, the typhoon could bring heavy to intense rains that could set off landslides and flash floods, the forecasters said. Storm warnings have been raised in 25 provinces across the main northern island of Luzon, restricting sea and air travel.
After the Philippines, the Hong Kong Observatory predicts Mangkhut will plow into the Chinese mainland early Monday morning south of Hong Kong and north of the island province of Hainan. Though it will weaken from a super typhoon to a severe typhoon, it will still be packing sustained winds of 175 kph (109 mph).
The observatory warned of rough seas and frequent heavy squalls, urging residents of the densely populated financial hub to "take suitable precautions and pay close attention to the latest information" on the storm.
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.
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On the Chinese mainland, the three southern provinces of Guangdong, Guangxi and Hainan are coordinating preparations, including suspending transport and moving people to shelter inland, the national meteorological agency reported.
Guangdong, China's manufacturing hub, has set up 3,777 shelters, while more than 100,000 residents and tourists have been moved to safety or sent home. The province has recalled more than 36,000 fishing boats to port, while train services between the cities of Zhanjiang and Maoming have been suspended and all ferry services between the Guangdong and Hainan have been put on hold.
Fujian province to the north of Guangdong is also closing beaches and tourist sites and preparing other measures depending on conditions, the agency reported.
Philippine Office of Civil Defense chief Ricardo Jalad told an emergency meeting led by President Rodrigo Duterte that about 4.2 million people in Cagayan, nearby Isabela province and outlying regions are vulnerable to the most destructive effects near the typhoon's 125-kilometer (77-mile) -wide eye. Nearly 48,000 houses in those high-risk areas are made of light materials and vulnerable to Mangkhut's ferocious winds.
Across the north on Thursday, residents covered glass windows with wooden boards, strengthened houses with rope and braces and moved fishing boats to safety.
Cagayan Gov. Manuel Mamba said by telephone that evacuations of residents from risky coastal villages and island municipalities north of the rice-and corn-producing province of 1.2 million people have started and school classes at all levels have been canceled.
"The weather here is still good but we're moving them now because it's very important that when it comes, people will be away from peril," Mamba said.
A change in the typhoon's track prompted authorities to rapidly reassess where to redeploy emergency teams and supplies, Mamba said.
Duterte asked Cabinet officials from the north to help oversee disaster-response work if needed, and told reporters it was too early to consider seeking foreign aid.
"It would depend on the severity of the crisis," Duterte said. "If it flattens everything, maybe we need to have some help."
The typhoon is approaching at the start of the rice and corn harvesting season in Cagayan, a major agricultural producer, and farmers were scrambling to save what they could of their crops, Mamba said. The threat to agriculture comes as the Philippines tries to cope with rice shortages.
Officials said other northern provinces started evacuating residents Thursday from high-risk areas, including in northern mountain provinces prone to landslides.
Duterte canceled his appearance at a missile test firing aboard a navy ship off northern Bataan province due to the approaching typhoon.
On Guam, where Mangkhut already passed, residents dealt with flooded streets, downed trees and widespread power outages. Government agencies were conducting damage assessments and clearing roads, according to the Pacific Daily News.
About 80 percent of the U.S. territory was without power but it was restored by Thursday morning.
Mangkhut, a Thai word for the mangosteen fruit, is the 15th storm this year to batter the Philippines, which is hit by about 20 a year and is considered one of the world's most disaster-prone countries. Typhoon Haiyan left more than 7,300 people dead or missing and displaced over 5 million in the central Philippines in 2013.
Associated Press writer Christopher Bodeen contributed to this report.