TAIPEI:  At least nine people were killed in a fire at a golf ball factory in southern Taiwan over the weekend, including four firefighters who died in an explosion, officials said Monday.

The fire, which began Friday evening and raged all night, also injured more than 100 people, mostly workers in the factory in Pingtung county, according to the local government.

One person was still listed as missing as further testing was required to verify the identity of some body fragments found at the scene, a county official told AFP.

President Tsai Ing-wen and other top officials visited the scene Saturday to express condolences to the victims’ families and vowed to investigate the cause of the fire.

An official with the Pingtung Fire Department told local media that chemical peroxide stored inside the factory could have been the cause of the one large and several smaller explosions.

Several people were trapped inside due to the blasts, which caused a section of the factory roof to collapse.