(CNN) -- Landslides unleashed by tropical depression Parma across the Philippine province of Benguet have killed at least 122 people and left 31 missing, officials said Friday.
A boatman transports three empty wooden coffins on the edge of Laguna Lake east of Manila on Thursday.
Four people had been found alive in debris, and at least 22 had been injured by landslides that started Thursday afternoon and continued all night, affecting several municipalities, said Elmer Foria, police senior superintendent.
Parma, which had been downgraded from a typhoon, poured more rain onto sodden and already weakened ground.
Flooding had inundated 32 towns and two cities, Dagupan and Urdaneta, according to Rocky Baraan, provincial administrator of Pangasinan. Some 35,000 people had fled to evacuation centers, the official Philippines News Agency reported, citing the Provincial Disaster Coordinating Council.
The worst-hit areas included Bayambang, Alcala and Basista, the news agency reported.
People clambered onto rooftops as floodwaters rose, calling and texting for help. Rescue trucks were hampered by floodwaters that reach the roofs of single-story houses, Baraan said. About 16 rubber rescue boats had been deployed.
Since the rains started in central Luzon, three dams in the Pangasinan area have been releasing vast amounts of water -- up to 10 million cubic meters per hour at one dam, dam officials said.
Water passing through the three dams -- the Ambuklao, the Binga and the San Roque -- is rushing into the Agno River, which has been swollen since Thursday and affects seven towns in eastern Pangasinan, dam officials said.
Water released from the San Roque dam has contributed to the flooding in eastern Pangasinan, acknowledged Alex Palada, division manager for flood forecasting and warning of the National Power Corporation. Dam officials had no choice but to maintain safe water levels, he added, noting that he alerted Pangasinan Governor Amado Espino. The governor started to evacuate residents Thursday when the Agno River started to rise, Palada said.
In the last several days, water has become the Philippines' biggest enemy, as Parma, locally known as "Pepeng," dumped as much as 36 inches (91.4 centimeters) of rain in some parts of the nation of islands, compounding misery in areas already flooded by earlier storm Ketsana.
Parma was forecast to have winds of no greater than 39 mph (63 kph) by Friday.
The U.S. Navy was expected to join rescue operations in Pangasinan, according to the agency.
Journalist Lilibeth Frondoso and CNN's Judy Kwon contributed to this report.