Story highlights Koppu, known as Lando in the Philippines, had sustained winds of 240 kph (149 mph)

Storm's strength is equivalent to a high-end Category 4 hurricane

Storm expected to crawl over Luzon island over three days, with threats of severe flooding

(CNN) Super Typhoon Koppu's eye smashed into northern Philippines' Luzon island with ferocious winds and rain early Sunday, just the early stages of what forecasters fear could be a three-day period of floods and landslides.

Koppu, known as Lando in the Philippines, had sustained winds of 240 kph (149 mph), a strength equivalent to a high-end Category 4 hurricane.

Koppu's eye made landfall at about 1 a.m. local time over Casiguran, a coastal city of about 25,000 people on Luzon, the country's largest and most populous island.

Even before the eye hit, the storm's outer bands lashed the country's east coast with heavy rain. Casiguran had 105 mm (4.1 inches) by late Saturday night, while Virac, on an island to the south, had 166 mm (6.5 inches).

The country's PAGASA weather service warned of likely significant damage to buildings and trees near the eye, and of dangerous storm surges that could rise as high as 3 meters (9.8 feet) along the coast.

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