BBC
Many were trapped in their homes as the flash floods coincided with high tides. In some places entire villages are reported to have been swept away.
Authorities have been criticised for not giving enough warning of the storm's severity.
However the state disaster agency said adequate warnings had been given to officials and residents three days before it reached land on Friday.
The BBC's Kate McGeown in the capital Manila says most of the 20 typhoons and major storms that hit the country each year affect the north - and many in Mindanao were unprepared for the severity of Tropical Storm Washi.
'Overwhelming'
The major ports of Cagayan de Oro and Iligan were among the areas worst hit on Friday night.
The scale of the disaster has forced the local authorities to issue an appeal for body bags and coffins.
"It's overwhelming. We didn't expect these many dead," said Benito Ramos, head of the government's disaster response agency.
The Philippines Red Cross is helping co-ordinate the search for those missing with the government and other aid agencies.
"Our office was swamped with hundreds of requests to help find their missing parents, children and relatives," said Gwendolyn Pang, Red Cross Secretary-General.
Most of the dead were women and children, Ms Pang said.
She said many bodies remained unclaimed, raising the possibility that entire families had been swept away.
Food and water are also urgently needed for the many displaced people.
Almost 35,000 people were still sheltering in evacuation centres on Sunday, the National Disaster Risk Reduction and Management Council said.
But others are living in the remains of their homes, with no electricity or running water.
Some of the survivors told of remarkable escapes after their villages were hit by floodwater.
One woman said she survived - along with eight family members and neighbours - by sitting on the tin roof of her house as it drifted down a river and miles into the open sea, where they were rescued by a cargo ship.
"There was a deafening sound followed by a rush of water. We found ourselves in the river and the current took us out to the sea," Carmelita Pulosan, 42, from Cagayan de Oro, told Reuters.
"The current was very strong. God is really good to us. He saved my family," she said.
The storm came ashore as many people slept
The number of people killed in the Philippines by floods triggered by Tropical Storm Washi has risen to 650.
Soldiers and volunteers are still searching for the 800 people reported missing on southern Mindanao island.Many were trapped in their homes as the flash floods coincided with high tides. In some places entire villages are reported to have been swept away.
Authorities have been criticised for not giving enough warning of the storm's severity.
However the state disaster agency said adequate warnings had been given to officials and residents three days before it reached land on Friday.
The BBC's Kate McGeown in the capital Manila says most of the 20 typhoons and major storms that hit the country each year affect the north - and many in Mindanao were unprepared for the severity of Tropical Storm Washi.
'Overwhelming'
The major ports of Cagayan de Oro and Iligan were among the areas worst hit on Friday night.
Continue reading the main story
“Start Quote
Carmelita Pulosan Villager in Cagayan areaThe current was very strong. God is really good to us. He saved my family”
Hundreds of bodies have been found in each of the two cities - many piled up in makeshift morgues.
Other bodies are gradually being washed ashore along the northern Mindanao coastline or are being found floating at sea.The scale of the disaster has forced the local authorities to issue an appeal for body bags and coffins.
"It's overwhelming. We didn't expect these many dead," said Benito Ramos, head of the government's disaster response agency.
The Philippines Red Cross is helping co-ordinate the search for those missing with the government and other aid agencies.
"Our office was swamped with hundreds of requests to help find their missing parents, children and relatives," said Gwendolyn Pang, Red Cross Secretary-General.
She said many bodies remained unclaimed, raising the possibility that entire families had been swept away.
Food and water are also urgently needed for the many displaced people.
Almost 35,000 people were still sheltering in evacuation centres on Sunday, the National Disaster Risk Reduction and Management Council said.
But others are living in the remains of their homes, with no electricity or running water.
Some of the survivors told of remarkable escapes after their villages were hit by floodwater.
One woman said she survived - along with eight family members and neighbours - by sitting on the tin roof of her house as it drifted down a river and miles into the open sea, where they were rescued by a cargo ship.
"There was a deafening sound followed by a rush of water. We found ourselves in the river and the current took us out to the sea," Carmelita Pulosan, 42, from Cagayan de Oro, told Reuters.
"The current was very strong. God is really good to us. He saved my family," she said.
Comments