Koppu, the second strongest storm to hit the disaster-plagued Southeast Asian archipelago this year, had also forced more than 60,000 people from their homes, authorities said.
After making landfall yesterday morning on the east coast of Luzon, the Philippines' biggest island, the slow-moving typhoon brought heavy rain to some of the nation's most important farming areas.
"I've never seen anything like this. It's the worst flood I've seen in my entire life," farmer Reynaldo Ramos, 68, told AFP as he walked through knee-deep water in Santa Rosa, about two hours' drive north of Manila.
"The floods are rising fast and some people are now on their rooftops," Lontoc told AFP, but added there were not enough rescuers and he did not know how many have been saved.
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Lontoc said many thousands of people may be stranded in those villages, although it was too early to determine an exact number.
Authorities confirmed at least 16 people had died because of the storm, and the death toll was expected to rise as full accounts from badly hit villages were gathered.
In Santa Rosa, water buffalo, pigs, goats, dogs, washing machines and furniture lined the sides of a storm-tossed highway, where about 200 residents had been seeking refuge from the floods since last night.
Jun Paddayuman, 27, in shorts and a white singlet caked with mud up to his chest, pointed to his nearby house, where flood waters had risen to the roof.
"The waters arrived suddenly. We did not expect it at all," he told AFP.
When the waters first appeared in his house, Paddayuman said he waded to the highway, helping his eight-months pregnant wife and three-year-old son to safety.
Nearby, two men pushed pigs placed on top of truck tyre inner tubes through chest-deep floods in a valiant attempt to save their hog farm.