Relatives of missing residents from a 16-storey apartment complex felled by a powerful earthquake in Taiwan that killed 13 people were praying for miracles Saturday as rescuers scoured the rubble for survivors.

The cluster of buildings in the historic southern city of Tainan were full of families who had gathered for Lunar New Year celebrations when it collapsed, with residents still trapped inside on Saturday night and the death toll rising, AFP reported.

Tainan bore the brunt of the 6.4 magnitude quake and the disaster zone centers around the residential complex containing almost 100 homes which were toppled.

The four blocks at the Wei-kuan complex were left lying on their sides with twisted metal girders exposed and clouds of dust rising from the jumbled concrete.

Among the 11 people killed when the apartment buildings collapsed were a 10-day-old baby girl and two other children, the National Fire Agency said.

The other two victims were killed in different parts of the city by falling debris, the agency said.

Around 800 troops have been mobilized to help the rescue effort with one elderly woman plucked from the rubble by a crane late Saturday night.

A senior army official at the scene said around 20 were still trapped in one of the buildings.

Relatives huddled by the ruins late Saturday, hoping for news of their loved ones.

Rescue workers told AFP that two of the toppled buildings fell against the other two blocks in the complex, crushing them.

Officials said there were 256 people registered as living in the complex, which contained 96 apartments.

More than 250 have been rescued so far, with more than 40 hospitalized.

Interior minister Chen Wei-jen said he feared there may have been more people in the building than usual as family members would have returned to celebrate the Lunar New Year holidays next week.

Officials said several blocks had collapsed or half collapsed in other parts of the city, with some buildings left leaning at alarming angles.

Across Tainan, more than 400 people were injured, with over 60 hospitalized.

Around 250,000 were still without water, authorities said, and more than 2,000 homes without electricity.

The quake struck at a depth of 10 kilometers (six miles) at around 4:00 am (2000 GMT Friday), 39 kilometers northeast of Kaohsiung, Taiwan's second-largest city.

Taiwan lies near the junction of two tectonic plates and is regularly hit by earthquakes.

The island's worst quake in recent decades was 7.6 magnitude in September 1999, killing around 2,400 people.