Torrential monsoon rains flooded half of the Philippine capital on Tuesday, killing at least 16 people as rampaging waters swept away homes, destroyed bridges and triggered a landslide in a shanty town.
Some residents were marooned on their roofs as parts of Manila were submerged in waters above head height in the worst flooding to hit the chaotic city of 15 million people since hundreds of people died three years ago.
"Right now we're on a massive rescue operation," Office of Civil Defence director Edgardo Ollet told AFP, warning the death toll would rise after people had ignored warnings to leave their homes.
"We are positive we still have more dead because there are some who won't evacuate."
Bad weather from seasonal southwest monsoons and Typhoon Saola had already pounded Manila and nearby areas for over a week, soaking the ground and raising dam levels to capacity.
Meteorologists said more than half the amount of rain normally seen in August then fell on the city in 24 hours, and warned the deluge would continue overnight and into Wednesday.
Rescue workers on rubber boats and military trucks were deployed in the flooded areas to pick up stranded people on Tuesday.
But they could not reach all areas and residents took to social media to appeal for help. On Twitter, #rescuePH quickly gained currency as the main hashtag used by people to send or gain information about the floods.
In the worst reported incident, nine people from the same family died in a landslide on a mountainous area of northern Manila near the city's reservoir that is populated by thousands of mainly illegal squatters.
"They were buried alive. It happened suddenly. We heard a crash, and then people crying out in pain," Honeyleta Ibrega, a neighbour of the landslide victims, told AFP.
A bus driver drowned in central Manila and six other people were confirmed to have drowned in surrounding areas, according to a government hospital and the civil defence office.
Tuesday's deaths brought the number of people killed by the monsoon rains across the Philippines over the past week to 69, according to authorities.
Another 80,000 people in and around Manila were in schools, gymnasiums and other government buildings set up as evacuation centres, according to the government.
However countless others were seeking shelter with friends or relatives, or hoping to wait out the crisis in their homes.
The Philippines has millions of people living in shanty towns, and the scale of a crisis such as Tuesday's flooding often means people have to fend for themselves.
Angie Angeles, a 33-year-old housewife, who had moved her family of nine and some of their salvaged belongings onto their roof in a lower-class southern district of Manila, said she intended to remain at home.
"We have no place else to go. There is no place to sleep at the evacuation centres," Angeles told AFP as the water was waist deep in her home around lunchtime on Tuesday.
Schools, financial markets and most government and private offices were also shut on Tuesday, while power was turned off in some parts of the city as a precautionary measure with the waters seeping into electrical facilities.
The breadth and ferocity of the floods brought back memories of tropical storm Ketsana, which killed 464 people as 80 percent of the capital was flooded in September, 2009.
Government weather forecaster Glaiza Escullar told AFP that Tuesday floods were close to the levels seen during Ketsana. However she said the 2009 floods were more dangerous because they were more sudden.