Search and rescue teams have worked around the clock since the magnitude 6.4 earthquake struck before dawn on Saturday, its efforts centred around the collapsed 17-storey Wei Guan residential building, where at least 15 of the deaths have occurred. Among them was a newborn baby, just 10 days old.

Sonar equipment and sniffer dogs had found signs of life from at least 29 people trapped in the rubble, officials said, while local media reported an 11-year-old boy was communicating with family and rescuers through Line, a popular mobile chatting application.

Rescue crews have already pulled  247 survivors out of the building, among 340 rescued throughout Tainan, where nine other buildings collapsed and numerous others were severely damaged.

Tragically, Saturday's quake came just before the start of Lunar New Year celebrations – the most important family holiday on the Chinese calendar. While the Wei Guan building had 256 registered residents, local officials believe the numbers actually inside were greater as families hosted guests who had travelled from afar for the holiday. The early hour the quake hit also meant residents were often asleep and slow to react.

Dozens of distraught relatives and loved ones watched anxiously from behind security barricades, rugged up in beanies and down jackets amid the wintry conditions. Local media reported the story of one woman who said she was still waiting on news of seven relatives who were still missing.

"She's not answering my phone calls ... I am trying to hold my emotions and stay strong. I'll do that until I find her," said one woman who told Reuters she was waiting to hear from her 24-year-old daughter, who lived on the fifth floor of the complex.

"Nothing matters but to get her out. The lady living across the hallway was rescued yesterday. I know they will find her, but I have also planned for the worst."

Huang Yu-liang said he was waiting for news of his brother, sister-in-law and their two children.

"I rushed here and saw the collapsed building and I was in shock," he told the news agency AFP. "Their building is at the bottom [of the wreckage]. I am praying for miracles."

The spectacular fall of the 17-storey residential building immediately raised questions about its construction. Taiwan is regularly rocked by earthquakes and buildings are meant to be designed to withstand both strong tremors and typhoons, which are also common. Taiwanese Interior Minister Chen Wei-jen said there would be an investigation into whether the building met construction requirements.

Residents told of their horror as the quake hit, with survivors pulled bleeding and crying from the ruins, some in just their underwear. Other tales of survival included one woman who used a hammer to break out of her crushed home, and a man who fashioned a rope from tied clothes to lower himself to safety.

with agencies