An earthquake has toppled several buildings in the south Taiwan city of Tainan, killing at least three people.

Rescue teams were trying to reach people trapped in rubble after the magnitude 6.4 quake struck early on Saturday as people were sleeping.

A baby and one other person died after a high-rise residential block collapsed. More than 220 people have been rescued.

President Ma Ying-jeou is on his way to Tainan, a city of two million people.

The quake was shallow, meaning its effects would have been amplified, the US Geological Survey (USGS) said.

Television pictures show rescue workers frantically trying to reach people trapped in collapsed buildings, using ladders to climb over piles of rubble.

Taiwan's official news agency said at least 23 people had been injured in the multi-storey residential building, where about 200 people were believed to be living in about 60 households.

Tainan resident Emma told BBC World News people feared further tremors. "I felt the quake, it was terrible," she said.

Irving Chu was in a hostel in central Tainan. He said he had been woken up by a tremor lasting about 40 seconds.

"It was a violent jerking motion," he told BBC World News. "The entire room was shaking. We were just holding on to things. We were shaken up."

Barry Knapp, a British man in Taiwan, said he was 240km (150 miles) north of Tainan but still felt the tremor.

"I was just in bed, about to fall asleep, and shaking started happening," he told BBC Radio 5 Live.

"It was going on for about 20 to 30 seconds and it came in waves. It was shaking and then it eased off, but then it started shaking even harder."

The earthquake struck as people were getting ready for Chinese New Year.

"It has come at a bad time," journalist Jay Chen told the BBC.

"Sunday is New Year's Eve. People were preparing to celebrate and now many people will be homeless."

There were also reports of power outages.

Saturday's quake was felt in the capital Taipei 300 km away and there have since been several aftershocks.

A 7.6 magnitude quake in central Taiwan in 1999 killed more than 2,300 people.

Taiwan lies near the junction of two tectonic plates and often sees tremors.