Swollen rivers burst their banks and unleashed waist-deep floods on shanty towns in the cities of Malaybalay and Valencia on Mindanao island this week, provincial civil defence chief Ana Caneda told AFP.
Heavy rains have swamped the region since late last month and the government warned residents of vulnerable areas, including riverbank shanties, to evacuate, but some refused, she said.
"They may not have relatives to go to and don't want to go to the evacuation centers so they (chose) to sit it out," Caneda said, adding that some had refused to leave their properties unguarded.
Rescuers recovered the corpses of five shantytown residents Wednesday when monsoon rains let up for the day, but three other residents remain missing, she added.
Caneda said the floods were brought on by a seasonal monsoon and were not related to Super Typhoon Soudelor, which is threatening Taiwan and China.
Hundreds of people are killed in natural disasters each year in the Philippines, which is battered by an average of 20 typhoons and tropical storms annually.