KAOHSIUNG, Taiwan: Heavy machinery pulled vehicles from huge trenches gouged by explosions along an underground pipeline in Taiwan’s second-largest city that killed at least 25 people and injured 267.

The series of five explosions from about midnight Thursday to early Friday struck a densely populated industrial district in the port of Kaohsiung where petrochemical companies operate pipelines alongside the sewer system under city streets. The cause of the disaster was being investigated.

Four firefighters were among the victims when the blasts went off hours after they’d been called to investigate gas leaks. At least six fire trucks were flung into the rubble.

The blasts sent flames shooting into the sky and hurled concrete and cars through the air, leaving meter (yard) -deep trenches down the middle of several roads.

Three people remained missing and many of the injured were still receiving emergency treatment.

The disaster was Taiwan’s second in as many weeks following the crash of a TransAsia Airways prop jet on the island of Penghu on July 23 that killed 48 people and injured 10.

“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 explosions were believed caused by leaking propene, a petrochemical material not intended for public use, said Chang Jia-juch, director of the Central Disaster Emergency Operation Center. Chang said the cause and location of the leaks were unknown.

The exploded gas line belongs to government-owned CPC Corp., which told The Associated Press there were no signs of problems before the explosions.