Thousands of residents in the Philippines lost their homes in flash flooding caused by heavy rains over the Christmas weekend. The death toll has now climbed to at least 51, while authorities reported earlier this week that 19 people are still missing, according to The New York Times.

At the time, over 56,000 people were placed in emergency shelters, and over 4,500 homes were damaged. In the southern province of Misamis Occidental, photos showed rescuers carrying an elderly woman on a plastic chair as they made their way through deep water to higher ground.

The flooding was caused by a weather phenomenon called a “shear line,” a narrow zone where wind velocity changes drastically as cold and warm air meet. The shear line triggered heavy rains, according to the weather bureau. The disaster forced at least 22 cities and municipalities to declare a state of calamity.

Thousands remain in shelters, and the government sent food and other essentials, deployed heavy equipment for clearing operations, and provided iron sheets and shelter repair kits, according to officials. Homeowners in the area said that uprooted trees and large waves damaged seaside homes.

Mindanao’s northern region reported the highest death toll. According to the National Disaster Risk Reduction and Management Council, 25 deaths were reported there. The council said that most of those drowned. Those missing include fishermen and people from capsized boats.

Ivy Amor Amparo, a hospital worker from Gingoog city in Misamis Oriental province, and six of her family members are now living in a small space in their damaged home. She said that her father used 5,000 pesos (about $90) of cash aid from the local government to build a temporary shelter, according to The Washington Post.

The council said communities have been left with damaged roads and bridges and disrupted water and power. Teams from the capital, Manila, were sent to communities with little to no clean water to help set up water filtration systems.