One resident nearby said he heard an explosion around 2:40 a.m. and then saw the building burning as people outside yelled for those inside to get out and cars began honking their horns to alert residents.
The fire was extremely fierce and as a result, many floors were severely burned, the department said in a statement, adding that the age of the building and amount of debris collected in its stairwells had accelerated the fire and hampered rescue efforts.
The fire was extinguished around dawn and rescue operations had concluded by Thursday afternoon, with 55 people sent to the hospital.
According to Taiwan’s Central News Agency (CNA), Kaohsiung’s police said the possibility of arson had not been ruled out and that four people had been taken into custody for questioning but there were not yet any suspects.
The 40-year-old building in the popular tourist district of Yancheng had been partly abandoned, with residents only living on the building’s upper levels. Described as a “city within a city,” it was once one of the busiest in the district, housing a cinema, market and serving as a red-light district, according to local media reports. Because of its checkered past, it was known among locals as Kaohsiung’s first haunted house.