Three workers were killed and 12 injured on Friday when a water tank burst at a Samsung Fine Chemicals plant in South Korea, a report said, citing police.
Yonhap news agency said the 1,300-tonne water tank was being filled to detect any cracks as part of a stress test, but erupted at around the 1,000 tonne mark.
Workers were hit by flying debris and the tank's supporting structures.
Hospital officials warned the death toll could rise as some of the injured were critical, the agency added in its report datelined from the southeastern industrial city of Ulsan.
Samsung Engineering, a unit of conglomerate Samsung Group, was building the tank for SMP, a joint venture between Samsung Fine Chemical and MEMC of the United States.
Samsung officials were criticised for downplaying the accident and blocking reporters from the scene.
The company initially announced that five to six workers sustained injuries.
In January, one Samsung worker died and four others were injured following a deadly toxic chemical leak at a chip-making plant.
Samsung is the world's top maker of smartphones, memory chips and flat-panel TVs.