Scores of aftershocks have hampered rescue efforts as emergency personnel comb through collapsed buildings in search of survivors after a powerful earthquake killed at least 10 people near Taiwan's tourist city of Hualien.
The coastal city was hit just before midnight on Tuesday by a magnitude 6.4 quake that injured 270 people. Four buildings collapsed, officials said, and seven people were still missing.
Rescuers stepped up efforts at one of the worst-hit structures, a 12-storey building that housed apartments and a small hotel, where authorities believe most of those still missing to have been, including several foreigners.
Thick steel girders propped up the heavily leaning structure to keep it from collapsing further, with the lower floors having already caved in.
"Everyone was surprised," said Huang Chang Po, the 58-year-old owner of a unit in the building, built in 1994.
"We have strong earthquakes all the time in Hualien and it's really bizarre that our building collapsed," he told Reuters.
At an emergency meeting on Thursday, other residents and owners raised concerns about possible recent modifications and demanded a structural check by engineers to determine the cause of the collapse.
It was too early to ascertain the cause, however, said Chang Cheng Chen, an engineer from a regional architects' association.
"It requires a thorough technical inspection, which may take two to three months," he said.
More than 220 aftershocks followed the main quake, including a 5.7 quake late on Wednesday.
Authorities "would not give up" on disaster relief efforts, Taiwan's President Tsai Ing-wen said during her second visit to the quake-hit area on Thursday.
Lin Tzu Wei, an official at the Central Weather Bureau, said continued vigilance of seismic activity was needed.
"We have not seen a sign of a slowdown yet," he told Reuters by telephone. "We need to continue to monitor the situation for one to two days... this is quite a rare event."
More than 600 soldiers and 1300 police spread out to help the rescue effort, along with a team from Japan. The government said three mainland Chinese were among the dead.
Chen Deming, president of China's Association for Relations Across the Taiwan Strait, said the mainland was willing to help with relief efforts, such as sending teams to the island. Taiwan authorities declined, however.
More than 800 people sought refuge in shelters overnight, many too scared to stay home as aftershocks fuelled panic.
Hualien, whose rugged Pacific coastline and picturesque Taroko Gorge National Park are a major tourist draw, is home to about 100,000 people.
Taiwan, a self-ruled island that China considers its own, lies near the junction of two tectonic plates and is prone to earthquakes.