The magnitude 6.4 quake struck just before 04:00 (20:00 GMT Friday) when most people were at home asleep.
A baby was among at least four people killed when a high-rise building, containing 100 homes, collapsed.
At least 30 people remain missing. Tainan's mayor said people were alive but trapped under the rubble and all means would be used to rescue them.
President Ma Ying-jeou, who toured the city of two million, said shelters would be set up for those who had lost their homes.
Television pictures showed rescue workers frantically trying to reach people trapped in collapsed buildings, using ladders to climb over piles of rubble.
One of the worst affected was the 17-storey Wei Kuan apartment complex, home to at least 256 people.
More than 200 people were rescued, but a baby, young girl and two adult men did not survive, officials said. At least 70 people were taken to hospital.
Interior Minister Chen Wei-jen said he feared more people may have been in the fallen apartment block than usual as families gathered to celebrate Chinese New Year.
He said investigators would examine whether the building's construction met requirements.
Residents told how they were able to escape from their homes in the block, using their own tools and ladders.
"I used a hammer to break the door of my home which was twisted and locked, and managed to climb out," one woman told local TV.
Another man tied clothes together to make a rope and lowered himself from the ninth floor to the sixth floor below, Apple Daily reports.
0 Comments
Share and comment. Enjoy!