Xinhua news agency of China, which also took the brunt of the deadly storm, quoted Vietnam's Central Steering Committee of Flood and Storm Control as saying the death toll from Son-Tinh had risen to seven as of Tuesday, while another five persons remained missing.
The storm also was blamed for injuries to 43 people as it landed in Vietnam with typhoon force after exiting the Philippines as a tropical storm of equal ferocity.
The worst-hit regions in Vietnam were the northern provinces of Thai Binh, Nam Dinh, Nghe An and Hai Phone, where the deaths occurred.
Vietnamese authorities said the storm had destroyed more than 13,000 homes, and flooded more than 48,400 acres of rice fields and 148,000 acres of other crops. Power supply in many provinces remained disrupted.
Preliminary damage estimate in Vietnam was about $130 million.
Son-Tinh also has been pounding China's southern Guangxi Zhuang province with heavy rains accompanied by strong winds since Sunday. At least one person has been reported dead, while another five from a sunken boat remained missing, Xinhua reported quoting the Ministry of Civil Affairs.
Xinhua said the storm also has been blamed in the sinking of dozens more boats along the China-Vietnam border region.
Tens of thousands of people had been evacuated before the storm hit China's Hainan and Guangxi Zhuang provinces.
Son-Tinh had weakened to a tropical storm but was causing flooding in many regions.
The storm struck the Philippines last weekend, causing heavy flooding and landslides that killed at least 27 people and left another nine missing, the Manila Times reported.
In other developments in the Philippines, a mild earthquake struck four cities in Metro Manila Wednesday morning, but no injuries or damage was reported, the Philippine Star reported, quoting seismologists.
The report said the magnitude-3 quake was felt in Quezon, Pasig, Makati and Taguig.
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