Manila: Back-to-back typhoons left at least 55 people dead and rescuers scrambling on Sunday to deliver food and water to hundreds of villagers stuck on rooftops for four days because of flooding in the northern Philippines.

Typhoon Nalgae slammed ashore in northeastern Isabela province on Saturday then barrelled across the main Luzon Island's mountainous north and agricultural plains that were still sodden from fierce rain and wind unleashed by a howler just day earlier. Nalgae left at least three people dead while Typhoon Nesat killed 52 others in the same region before blowing out on Friday.

Nalgae was whirling 200 kilometres over the South China Sea from the country's northeast toward southern China early on Sunday with sustained winds of 130 kilometres per hour and gusts of 160 kph, according to the government weather agency.

Its ferocious wind set off a rockslide in northern Bontoc province on Saturday, causing boulders to roll down a mountainside and smash on a passing van, where a passenger was pinned to death and another was injured, police said.

In northern Tarlac province's Camiling town, an uncle sought safety with his two young nephews as flooding rose in their village yesterday. But one of the children was swept away by rampaging waters and drowned while his uncle and brother remained missing. A drunk man drowned in flooding in a nearby village, provincial disaster officer Marvin Guiang said.

Nalgae roared through a similar path across areas on Luzon saturated by Typhoon Nesat, which trapped thousands on rooftops and sent huge waves that breached a seawall in Manila Bay. Nesat also pummelled southern China and was downgraded to a tropical storm just before churning into northern Vietnam on Friday afternoon, where flood warnings were issued and 20,000 people evacuated.

In the rice-growing province of Bulacan north of Manila, hundreds of residents in flooded Calumpit town remained trapped on rooftops in four villages for the fourth day, many of them desperately waving for help. Rescuers aboard rubber boats could not reach them because of narrow alleyways. Two air force helicopters would be deployed on Sunday to drop water and food packs to the marooned villagers, officials said.

Calumpit Mayor James de Jesus pleaded for more help from the national government.

"The ones waving for help are the ones who need to be rescued first because they have elderly people and children with them," de Jesus said. "We have a very big problem here, we're facing a long flooding."