The fatalities include one person hit by a tree toppled by strong winds and another who was crushed in a landslide spawned by heavy rains, said the disaster-monitoring council chief Benito Ramos.
Nine fishermen, who ventured out to sea in separate parts of the Philippines between Monday and Wednesday, have been listed as missing, but Ramos said the authorities had not given up hope that some of them may be found alive.
"Maybe these guys just took refuge in small islands. They might emerge anytime. We can't say they are dead. There is an effort to locate them," he told AFP.
The storm, which recorded maximum winds of 90 kilometres (56 miles) per hour, also caused flooding that derailed a train travelling through Sariaya town, southeast of Manila, leaving nine passengers injured, Ramos added.
Son-Tinh cut through the central islands of the Philippines earlier this week and on Friday was charted as moving west into the South China Sea at 22 kilometres per hour, the government weather station said.
The Philippines endures about 20 major storms or typhoons every rainy season.