The shallow 6.4 quake late caused at least four buildings in Hualien county to cave in and tilt dangerously, leaving over 200 people injured.
Rescue workers scrambled to search for survivors in buildings left tilting precariously on their foundations in the Taiwanese city of Hualien on Wednesday, after an overnight earthquake killed seven and injured more than 200.
Authorities said they could not verify how many residents were still missing after the 6.4-magnitude quake hit the popular tourist city late Tuesday.
Rescue efforts were focused early Wednesday on the Yun Tsui residential building, which also housed a restaurant, shops and a hostel. The quake left the 12-storey building leaning to one side, its lower floors pancaked.
The national fire agency said 143 residents from the building remained unaccounted for but it was not immediately clear whether those missing were trapped inside the building or not.
TRT World's Kerry Alexandra has more.
"I saw the first floor sink into the ground. Then it sunk and tilted further and the fourth floor became the first floor," said Lu Chih-son, 35, who saw 20 people rescued from the building.
"My family were unhurt, but a neighbour was injured in their head and is bleeding. We dare not go back home now. There are many aftershocks and we are worried the house is damaged," he said.
Chen Chih-wei, 80, said he was sleeping in his apartment on the top floor of the building when the quake struck.
"My bed turned completely vertical, I was sleeping and suddenly I was standing," he said.
He said he managed to crawl his way to a balcony to wait for rescue, adding that the quake was the strongest he had felt in more than five decades of living in Hualien.
Cranes prop up building
President Tsai Ing-wen visited the site Wednesday morning, where officials were going room by room looking for anyone trapped inside.
"Now is the prime time for our rescue efforts, our first priority is to save people," she said in a Facebook post.
At least four mobile cranes had been brought in on the back of trucks to help prop up the structure, a reporter on the scene said.
Liu Yan-hu, from the Hualien County Architects Association, told Apple Daily it looked like the building's main structure was intact.
Five more buildings, including a hospital and a hotel, were also damaged in the city, where roads were ripped apart and strewn with rubble.
The national fire agency said four people had been killed across the city with 225 injured.
Hualien is one of Taiwan's most popular tourist hubs as it lies on the picturesque east coast rail line and near to the popular Taroko Gorge.
Frequent aftershocks left some residents stranded in the open as they feared going back into buildings. Authorities said 830 people were in shelters Wednesday morning and some 1,900 houses were without power.
Officials said 117 people were rescued from damaged buildings so far.
The severely damaged Marshal Hotel had also crumpled into the ground as its bottom storeys disappeared.
"The lower floors sunk into the ground and I saw panicked tourists being rescued from the hotel," eyewitness Blue Hsu told AFP.
The quake hit just before midnight (1550 GMT) around 21 kilometres (13 miles) northeast of Hualien, according to the United States Geological Survey.
It followed almost 100 smaller tremors to have hit the area in the last three days and comes exactly two years since a quake of the same magnitude struck the southern Taiwanese city of Tainan, killing more than 100 people.
Most of the deaths from the February 2016 earthquake were from the 16-storey Wei-kuan apartment complex, which toppled on its side and buried many residents in the rubble.
It was the only high-rise in Tainan to crumble completely in the quake, which came two days before Lunar New Year, when many people were visiting relatives for the biggest celebration of the Chinese calendar.
The safety of the building was called into question immediately after the disaster, when metal cans and foam were found to have been used as fillers in the concrete. Residents said there had been cracks in the structure.
Five people were found guilty and sentenced to five years imprisonment over the disaster, including the developer and two architects, with prosecutors saying they "cut corners" that affected the building's structural integrity.
Taiwan lies near the junction of two tectonic plates and is regularly hit by earthquakes.
The island's worst tremor in recent decades was a 7.6 magnitude quake in September 1999 that killed around 2,400 people.