At least 25 people were killed and 267 others injured when five underground gas blasts ripped through Taiwan's second-largest city, authorities said as an inquiry was launched into the cause.
The explosions hurled concrete and cars through the air and blasted long trenches in the streets.
The series of explosions struck a densely populated area where petrochemical companies operate pipelines alongside the sewer system in Kaohsiung, a south-western port with 2.8 million people.
Firefighters called to the neighbourhood in the late evening to investigate a gas leak were among the victims when the blasts went off hours later, overturning at least six fire trucks in the rubble of pavement and dirt.
Four firefighters were among the 25 dead as well as some of 267 people injured, the National Fire Agency said. The death toll could rise, because many of the seriously injured are still being treated, officials said.
Three people were reported missing in the disaster, Taiwan's second in as many weeks following a plane crash on July 23 in which 48 people were killed.
"Last night around midnight, the house started shaking and I thought it was a huge earthquake, but when I opened the door, I saw white smoke all over and smelled gas," said Chen Qing-tao, 38, who lives 10 buildings away from the main explosion site.
The fires were believed to have been caused by a leak of propene, a petrochemical material not intended for public use, but the cause and source of the leak were not immediately clear, officials said.
The exploded gas line belongs to government-owned CPC Corp, which told the Associated Press it showed no signs of problems before the blasts. CPC officials at the scene declined to offer information about a possible cause.
Video from broadcaster TVBS showed residents searching for victims in shattered shopfronts and rescuers pulling injured people from the rubble of a road and placing them on stretchers while passers-by helped other victims on a pavement. Broadcaster ETTV showed rows of large fires sending smoke into the night sky.
Chang Jia-juch, director of the Central Disaster Emergency Operation Centre, said the leaking gas was most likely to be propene. The source of the leak was unknown. Mr Chang said, however, that propene was not for public use, and that it was a petrochemical material.
One of the fires, along a 33ft (10m) stretch of gas pipe, was still burning at midday, the National Fire Agency said on its website.
The government's disaster response centre said it was trying to prevent any knock-on gas explosions in the same place or nearby.
"In terms of what we can prevent, we're afraid another explosion could happen, as there is that possibility," said Hsu Lee-hao, an economics affairs ministry section chief staffing the disaster response centre. "We're afraid it could be in the same place or elsewhere."
Most of the injured were people outside on the street, often hit by rubble blown towards them or crushed by cars sent flying in the blasts, a police officer at the scene said. Police and firefighters were burned while trying to control blazes.
"I wanted to check on my friend working in the night market, but she was hit by rubble and is now still in the hospital," said Chang Bi-chu, 63, the door to whose house was warped by one of the blasts. "On the way I saw dead bodies. I felt really bad. After all there was just the air crash in Penghu last week."
A TransAsia Airways prop jet that took off from Kaohsiung crashed while trying to land in stormy weather in an archipelago in the Taiwan Strait on July 23. Forty-eight people were killed and 10 injured.
"The power is cut off in my house, there is no light and the fan doesn't work," Mr Chang added. "We don't have money to stay in a hotel and they're all booked anyway."
Kaohsiung Mayor Chen Chu said several petrochemical companies have pipelines built along the sewage system in Chian-Chen district, which has both factories and residential buildings. She warned people to stay away today.
"We have an intersection that's still burning," Ms Chen said at an emergency government meeting broadcast on television. She called the explosions Kaohsiung's worst gas-related accident in 10 years. "The city of Kaohsiung has opened nine relief shelters. We hope people can first evacuate to a safe place."
More than 1,100 were evacuated overnight.
Rescue workers expected to find few, if any, people in the rubble because no buildings collapsed, the disaster response centre said.
When police officers and firefighters investigated the major leak on Kaixuan Road earlier in the evening, they could not block it because they had not identified the source of gas. Those authorities were closest to the fire during the first explosion and therefore suffered burns.
People killed and injured elsewhere were standing, walking or driving in the streets, which are near a night market. Paramedics and a rescue dog were combing the area for survivors.
Power supplies to 12,000 people in the area were cut off, and 23,600 lost gas service.
The fire department received reports from residents of gas leakage at about 8:46 p.m., and the explosions started around midnight.
CCTV showed an explosion rippling through the floor of a motorcycle parking area, hurling concrete and other debris through the air. Mobile phone video captured the sound of an explosion as flames leapt at least 9m into the air.
One witness said he tried to help before paramedics arrived.
"I was on my scooter just across the street. Suddenly there was the explosion, a white car was blown toward me, and I saw the driver trapped in the car," said Wong Zhen-yao, 49, owner of a car repair shop in the disaster area.
"There was still fire nearby. I tried to pull the guy out but couldn't," he said. "Only after the smoke was gone did I realise there was such a big hole in the middle of the road."
The explosions left large trenches of up to 3ft (1m) deep running down the centres of four of the hardest-hit roads. The trenches were littered with soot-covered cars and pieces of pipe and edged with pavement slabs torn apart by the blasts. Burnt walls and toppled signs of shops lined Sanduo Road, near an elementary school.
The blasts affected an area of 0.8 to 1.2 square miles (2 to 3 sq km), and much of it has been sealed off.