Multiple gas pipeline explosions have killed 24 people and injured 257 others in Taiwan's second city, emergency officials said.

Witnesses said Thursday's blast in Kaohsiung sent flames shooting 15 storeys into the air, and entire blocks, packed with shops and apartment buildings, were set ablaze.

Firefighters called to the neighbourhood to investigate a gas leak were among the victims when the blasts went off, upending at least five red fire trucks amid the rubble of pavement and dirt.

"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,'' Chen Qing-tao, who lives 10 buildings away from the main explosion site, told the Associated Press.

Taiwan's Prime Minister Jiang Yi-huah said at least five blasts shook the streets of Kaohsiung, a port city of 2.8 million.

"The local fire department received calls of gas leaks late Thursday and then there was a series of blasts around midnight affecting a area of two to three square kilometres," the National Fire Agency said in a statement.

Chang Jia-juch, the director of the Central Disaster Emergency Operation Centre, said the leaking gas had been identified as propene, meaning that the resulting fires could not be extinguished by water. The source of the leak was unknown.

Kaohsiung Mayor Chen Chu said several petrochemical companies have pipelines built along the sewage system in Cianjhen, which has both factories and residential buildings.



Power was cut off in the area, making it difficult for firefighters to search for people who might be buried in rubble.

The Central Disaster Emergency Operation Centre said police and soldiers had been drafted in to help firefighters.

Emergency shelters were set up to house about 150 affected residents.