Relatives of the victims cry after an explosion in Kaohsiung, southern Taiwan, August 1, 2014. [Photo/Agencies]

Updates

16:10, Friday

The death toll in Thursday night's gas leak blast in Taiwan's second-largest city – Kaohsiung – has risen to 35, tw.people.com reported.

Other 267 people were reported injured with two firefighters still missing.

Power supplies to 7,536 households in the area were severed, and 23,600 households lost their gas supply. A total of eight shelters have been built with the capacity to help 1,110 people.

14:41, Friday

The death toll from the Kaohsiung blasts has climbed to 25 with 267 others injured, two firefighters are still missing, chinanews.com reported citing Taiwan-based BCC News Network.

13:22, Friday

Xi Jinping, general secretary of the Communist Party of China Central Committee, on Friday conveyed condolences to the victims in the gas leak explosions hitting Kaohsiung City in Taiwan on Thursday. [More] 

12:06, Friday

As of 9 am Friday local time, 271 others were injured. The number of casualties could continue to rise as the explosions caused a road surface to collapse and people might have fallen into the hollows, reported Xinhua news agency.

Related: 24 dead in Taiwan gas

TAIPEI -  At least 24 people were killed and 271 others injured when several underground gas explosions ripped through Taiwan's second-largest city overnight, hurling concrete through the air and blasting long trenches in the streets, authorities said Friday.

The series of explosions about midnight Thursday and early Friday struck a district where several petrochemical companies operate pipelines alongside the sewer system in Kaohsiung, a southwestern port with 2.8 million people.

The fires were believed caused by a leak of propene, a petrochemical material not intended for public use, but the source of the gas was not immediately clear, officials said.

Video from the TVBS broadcaster showed residents searching for victims in shattered storefronts and rescuers pulling injured people from the rubble of a road and placing them on stretchers while passersby helped other victims on a sidewalk. Broadcaster ETTV showed rows of large fires sending smoke into the night sky.

Four firefighters were among the 24 dead and 271 people were injured. The firefighters had been at the scene investigating reports of a gas leak when the explosions occurred, local media reported.

At least five blasts shook the city, the island's executive chief Jiang Yi-huah said.

Chang Jia-juch, the director of the island's disaster emergency operation center, said the leaking gas was most likely to be propene, meaning that the resulting fires could not be extinguished by water. He said emergency workers would have to wait until the gas is burnt away.

The source of the leak was unknown. Chang said, however, that propene was not for public use, and that it was a petrochemical material.

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.