A horrific fire at a golf ball factory in southern Taiwan over the weekend killed 9 people including four firefighters, according to officials on Monday.

The fire in Pingtung County that began on Friday and raged through the night into Saturday, injured over 100 people, primarily workers, and left one person missing, CNA reported.

Previously, officials had reported that five people were killed as a result of the fire.

A county official reported that further testing is needed to verify the identity of body fragments found at the scene.

Another county official was quoted by Taiwan’s Central News Agency as saying that the explosion that followed the fire in a building, caused a part of the building to collapse at about 6:10pm, resulting in the deaths of firefighters and workers.

Although the cause of the fire remains unknown, a fire department official told local media on Saturday that chemical peroxide stored inside the factory could have been the cause of the one large and several smaller explosions.

President Tsai Ing-wen visited the site of the tragedy on Saturday accompanied by other top officials to express condolences to the victims’ families and vowed to investigate the cause of the incident.

Taiwan is a significant producer of golf balls, with factories providing top brands including Callaway, TaylorMade, Bridgestone, Mizuno, and Wilson, according to its 2021 annual report.

The burned-down factory belonged to Launch Technologies, a major global supplier of golf balls.

According to the CNA, Launch Technologies, a company listed on the Taipei Exchange, exported around 260 million golf balls last year, making about one-fifth of the total sold worldwide with the US accounting for over 80% of company sales.

Taiwan’s Ministry of Labor announced on Saturday that it plans to initiate an occupational safety investigation into Launch Technologies and its parent company, citing past fines for inspection violations in an export processing zone.