Tropical Storm Kai-tak, known locally as Urduja, battered the area on Saturday with heavy rains, strong winds and flash flooding.
One police officer told AFP news agency "rocks as big as cars" had been dislodged by the rainfall.
About 88,000 people were forced to leave their homes ahead of the storm.
The storm has also disrupted ferry services, disaster officials said, leaving more than 15,000 passengers stranded, many of them trying to reach home for the Christmas holidays.
However, the storm weakened on Sunday and was downgraded to a tropical depression.
