Philippines officials said Monday they are preparing mass burials for hundreds of people who were killed when flash floods swept through two cities on southern Mindanao island over the weekend.

Officials said the the mass burials, beginning Tuesday, are necessary for health reasons, despite the objections of some relatives of the dead. The death toll was placed Monday at more than 600, most of them women and children. Estimates of the number of missing ranging as high as 800.

Lawrence Cruz, the mayor of hard-hit Iligan City, said authorities are worried about a health threat from the decomposing bodies.

“We have decided, after consultation with our city health officer, that we should start digging graves for the bodies and bury them temporarily because they are already in an advanced state of decomposition. People nearby might get sick if we do not bury the bodies.''

He said the mass burials were ordered on the advice of the city's health officer.

Rescue crews were still digging through mud and rubble on Monday, struggling to treat the bodies with proper dignity in spite of the lack of proper resources. In many cases, bodies had to be wrapped in plastic bags.

The flooding was caused by a tropical storm that swept through the southern Philippines Friday evening, dropping a month's worth of rain in 24 hours.

The flooding washed away riverside slum communities in the cities of Iligan and Cagayan de Oro, in some cases carrying away whole families as they slept.

Iligan farmer Romeo Lozano described opening his home to about 200 people, who weathered the storm on an upper floor of his house.

“If I had not opened our gate, many people would have died because they were already waiting and wanted to go upstairs. When I opened it, they all rushed to go inside our house, there is a roof top and we were all safe there. 200 of them, mostly children and elderly.”

He said most of the people he saved were children or elderly.

Almost 50,000 people who lost their homes remain in public shelters.