- 'Multiple' buildings have collapsed in the city of Tainan, in the south-west
- At least one is residential, and 'hundreds' are feared trapped in rubble
- So far five aftershocks registering at least 2.8 have taken place
Hundreds of people are feared trapped in collapsed buildings after a 6.4 magnitude earthquake struck Taiwan.
'Multiple' buildings - including at least one residential block - are said to have fallen in the city in Tainan following the quake which shook the island at about 4am on Saturday.
Pictures show buildings partially or completely destroyed, while video footage shows rescue workers wading through water after the mains burst.
At least five aftershocks of 3.8-magnitude or more have shook the city about half an hour after the initial quake, according to Taiwan's Central Weather Bureau.
The initial quake was very shallow, at depth of 6.2 miles (10 km), which would have amplified its effects, the United States Geographical Survey said.
At least 30 people have been rescued so far, with no reported fatalities.
Taiwan's Formosa TV showed images of police, firefighters and some troops in camouflage uniforms at the site of a collapsed residential building and said its reporters could hear the cries of some residents trapped inside
The firefighters were hosing down part of the building to prevent a fire, while others used ladders and a crane to enter the upper floors.
Lin Kuan-cheng, spokesman for the National Fire Agency, said: 'Four buildings have collapsed in Tainan City area. Search and rescue is under way and no casualties have been reported at this moment.'
Taiwan's China Post newspaper said on its website that more than one building had been toppled by the force, while other sources say power has been cut to large areas of the city.
Liu Shih-chung, an official with the Tainan City Government, said the city had set up an emergency response centre.
A Taiwan quake toppled a 17-storey apartment building in southern Tainan city on Saturday, and crews had so far rescued 123 people from the wreckage, a fire brigade official said.
There were no immediate reports of deaths from the 6.4 magnitude tremor, which struck before dawn.
"There are 60 households in that building," said Tainan City Government Fire Bureau information officer Lee Po Min, estimating that there might be about 240 people living there.
At least 30 people have been rescued after four buildings collapsed in the southern Taiwanese city of Tainan following a strong 6.4-magnitude earthquake that struck the island early on Saturday, officials said.
Images on television and social media showed a half crumbled seven-storey high rise which had lurched to one side. A rescue operation was under way in two buildings, officials said, with no fatalities reported so far.
"Four buildings have collapsed in Tainan City area. Search and rescue is under way and no casualties have been reported at this moment," Lin Kuan-cheng, spokesman for the National Fire Agency, told AFP.
The shallow quake struck at a depth of 10 kilometres (six miles) around 2000 GMT Friday, according to the US Geological Survey, 39 kilometres northeast of Kaohsiung, the second-largest city on the island and an important port.
The quake was initially reported as having a magnitude of 6.7, but was downgraded to 6.4.