FOUR workers of a machinery factory in Baoshan District were killed at noon today.

　　The workers of Shanghai Zhizhuo Machine Equipment Co Ltd on Shitai Road were killed at the scene in the blast happening at 12:20pm.

　　Another two men, who were injured in the blast, were rushed to the Baogang Hospital for treatment and they are in stable conditions. No open fire is seen at the scene and investigation is underway.

　　The blast happened when workers were repairing cathode rollers, and it is a production safety accident based on initial investigation results, the Shanghai Administration of Work Safety said.

　　A company in Kunshan in Jiangsu Province sent these cathode rollers for repair, according to the administration.

　　The company was registered with a capital of 10 million yuan (US$1.54 million) late 2011. It is a mechanical equipment manufacturer and focuses on the design, manufacturing and repair of machines and processing of metal machinery, according to its website.