A day after a 6.4 magnitude earthquake toppled a high-rise apartment building in the southern Taiwanese city of Tainan, killing at least 26 people and injuring hundreds, questions are being raised over the structural integrity of the 17-story Wei-guan Golden Dragon Building.

Liu Shih-chung, a senior government official in Tainan, reportedly said that television footage of the ruins of the commercial-residential building suggested the possibility of structural problems related to poor-quality reinforced steel and cement. Footage of the collapsed building — where rescue workers are scrambling to pull out over 100 people that are still trapped in the rubble — showed pillars reinforced with Styrofoam and empty tin cans — a problem that was also found in some of the buildings that collapsed in other parts of Taiwan during an earthquake in 1999.

Tainan’s government, however, said the building had not been listed as a dangerous structure, and Taiwan’s interior minister, Chen Wei-zen, said an investigation would examine whether the developer had cut corners and used shoddy building material to save costs.

“When it's completed, we'll punish those who should be held accountable,” Tainan Mayor William Lai reportedly said, adding the government had hired three teams of civil engineers to inspect the building.

The building, built in 1989, was the only major high-rise in the city that completely collapsed during the earthquake. So far, more than 170 people have been rescued from the rubble.

According to Reuters, residents of the building had frequently complained of problems, such as tiles falling from walls, malfunctioning lifts and blocked pipes, much before the quake.

“People from outside of the town … had no idea what was going on before they moved in,” the mother of a resident who was injured when then building collapsed Saturday, told Reuters. “They did not know the building was completed by the second developer after the first one went bust. They only found out after they signed the contract."